This is my LWC 
<template>
     <lightning-card title="" icon-name="custom:custom19">
        <lightning-file-upload
            label="Attach receipt"
            name="fileUploader"
            accept={acceptedFormats}
            record-id={recordId}
            onuploadfinished={handleUploadFinished}
            multiple>
    </lightning-file-upload>
    </lightning-card>
    <lightning-record-edit-form object-api-name="DMS__c" onsuccess={handleSuccess} onsubmit ={handleSubmit} >
        <div class="slds-grid">
            <div class="slds-col slds-size_1-of-2">
        <lightning-input-field field-name='Name'></lightning-input-field>
        <lightning-input-field field-name='Version__c'></lightning-input-field>
        <lightning-input-field field-name='Key_Words__c'></lightning-input-field>
        <lightning-input-field field-name='Doc_type__c'></lightning-input-field>
        <lightning-input-field field-name='Description__c'></lightning-input-field>
        </div>
        <div class="slds-col slds-size_1-of-2">
            <lightning-input-field field-name='Contract_LOB__c'></lightning-input-field>
            <lightning-input-field field-name='Active_Contract__c'></lightning-input-field>
            <lightning-input-field field-name='Competitor_Contract__c'></lightning-input-field>
            <lightning-input-field field-name='Folder__c'></lightning-input-field>
         </div>
        </div>
        <div class="slds-clearfix">
            <div class="slds-align_absolute-center">
        <lightning-button class="slds-m-top_small" type="submit" label="Upload"  onclick={showSuccessToast}></lightning-button>
        <lightning-button class="slds-m-top_small" label="Cancel" onclick={allowReset}></lightning-button>
        </div>
    </div>
    </lightning-record-edit-form>
</template>

Thefollowing is my .js file
import { LightningElement, api } from 'lwc';
import {ShowToastEvent} from 'lightning/platformShowToastEvent';
import POST from '@salesforce/apex/docUpload.POST';  
export default class Final extends LightningElement {
    @api recordId;
    get acceptedFormats() {
        return ['.pdf', '.png','.jpg','.jpeg'];
    }
    handleUploadFinished(event) {
        // Get the list of uploaded files
        const uploadedFiles = event.detail.files;
        let uploadedFileNames = '';
        for(let i = 0; i < uploadedFiles.length; i++) {
            uploadedFileNames += uploadedFiles[i].name + ', ';
        }
          var Name = component.get("v.Name");
            var Doc_type__c = component.get("v.Doc_type__c");
            var Active_Contract__c = component.get("v.Active_Contract__c");
            var Competitor_Contract__c = component.get("v.Competitor_Contract__c");
            var Version__c = component.get("v.Version__c");
            var Key_Words__c = component.get("v.Key_Words__c");
            var Folder__c = component.get("v.Folder__c");
            var action = component.get("c.POST");
            action.setParams({ file : uploadedFiles, Name : Name, Doc_type__c : Doc_type__c, Active_Contract__c : Active_Contract__c, Competitor_Contract__c : Competitor_Contract__c, Version__c : Version__c, Key_Words__c : Key_Words__c, Folder__c : Folder__c });
            action.setCallback(this, function(response) {
                var returnValue = response.getReturnValue();
                console.log('returnValue===>'+returnValue);
            
                component.set("v.message", returnValue);
            });
            $A.enqueueAction(action);
            this.dispatchEvent(
                new ShowToastEvent({
                    title: 'Success',
                    message: uploadedFiles.length + ' Files uploaded Successfully: ' + uploadedFileNames,
                    variant: 'success',
                }),
            );
    }
       
    handleSuccess(event) {
        console.log('onsuccess event ',event.detail.id)
        
    }
    handleSubmit(event) {
        console.log('onsubmit event Newcomp'+ event.detail.fields);
       
    }
    showSuccessToast() {
        const evt = new ShowToastEvent({
            title: 'Toast Success',
            message: 'Opearion sucessful',
            variant: 'success',
            mode: 'dismissable'
        });
        this.dispatchEvent(evt);
    }
    allowReset(event) {
        const inputFields = this.template.querySelectorAll(
            'lightning-input-field'
        );
        if (inputFields) {
            inputFields.forEach(field => {
                field.reset();
            });
        }
    }
}
my apex post callout is given
public with sharing class docUpload {
    
    public String resBody {get; set;}          
        @AuraEnabled
        public static String POST(Blob file, String Name, String Doc_type__c, String Active_Contract__c, String Competitor_Contract__c, String Version__c, String Key_Words__c, String Folder__c) {
            
            Http h = new Http();
    //    String fileName = 'leads.csv';
            String url = 'https://csv-file-upload.herokuapp.com/leads/' + recordId;
            String separationString = 'da5cbc76-39ba-4f80-8b81-090b82e90cf0';
            String str = file.toString();
       //     String csvBody = EncodingUtil.base64Encode(csvBlob);
            // decode 
            Blob decodedBlob = EncodingUtil.base64Decode(str);
            system.debug('string ==>'+decodedBlob);
            // convert to string
            String result = decodedBlob.toString();
            
            // assemble the body payload
            String header = '--' + separationString + '\nContent-Disposition: form-data; name="file"; filename="' + fileName + '"\nContent-Type: application/octet-stream\n\n';
            //String body = EncodingUtil.base64Encode(file) + '\n';
            String body = result + '\n';
            String footer = '--' + separationString + '--';
            String bodyPayload = header + body + footer;
            system.debug('PAYLOAD: ' + bodyPayload);
    
            HttpRequest req = new HttpRequest();
            req.setHeader('Content-Type', 'multipart/form-data; boundary=' + separationString);
            
            req.setEndpoint(url);
            req.setMethod('POST');
            req.setBody(bodyPayload);
            system.debug('REQUEST: ' + req);
    
            // Send the request, and return a response
            HttpResponse res = h.send(req);
            System.debug(res.getBody());
            return res.getBody();
        }
}