this is my test class and i'm not familiar in this error :

System.DmlException: Insert failed. First exception on row 0; first error: MIXED_DML_OPERATION, 
DML operation on setup object is not permitted after you have updated a non-setup object (or vice versa): 
User, original object: Account: []


My Test Class:
@isTest(seeAllData=true)
private class GHI_Portal_Login_Test {

    private static testMethod void testLogin() {
        RecordType rtContact = [SELECT Id FROM RecordType WHERE SObjectType='Contact' AND Name='Patient' LIMIT 1];
        Account acct = OSM_DataFactory.createAccount('test test');
        insert acct;
        Contact ctct = OSM_DataFactory.createContact('test','test',rtContact.Id);
        ctct.AccountId = acct.Id;
        insert ctct;
        
        
        User testUser = new User();
        testUser.Username= 'testUser11@company.com';
        testUser.Email = 'testuser1@company.com';
        testUser.Lastname = 'user';
        testUser.Firstname = 'test';
        testUser.Alias = 'test';
        testUser.CommunityNickname = '12346';
        List<Profile> prof = [select Id from Profile where Name = 'System Administrator' LIMIT 1];
        List<UserRole> role =  [select Id from UserRole where Name = 'finance'];
        testUser.UserRoleId = role[0].Id;
        testUser.ProfileId = prof[0].Id;
        insert testUser;
        
        User user = new User();
        user.Username= 'testUser1@company.com';
        user.Email = 'testuser1@company.com';
        user.Lastname = 'user';
        user.Firstname = 'test';
        user.Alias = 'test';
        user.CommunityNickname = '12346';
        List<Profile> prof1 = [select Id from Profile where Name = 'GHI Portal User' LIMIT 1];
        user.ProfileId = prof1[0].Id;
        user.ContactId = ctct.Id;
        
        System.debug ( JSON.serializePretty( testUser ) );
        
        
        
        PageReference pageRef = Page.GHI_Portal_Login;
        GHI_Portal_Login controller = new GHI_Portal_Login();
        Test.setCurrentPage(pageRef);
        
        Test.startTest();
        System.runAs(testUser) {
            insert user;
        }
        controller.username = 'testUser1@company.com';
        controller.password = '123456';
        controller.login();
        Test.stopTest();
    }

}