Support Casdoor SSO autentication in social-app-django

[hsluoyz]

• https://github.com/python-social-auth/social-app-django
• https://studygyaan.com/django/how-to-add-social-login-to-django
• https://medium.com/@namantam1/login-with-facebook-and-google-in-django-using-social-auth-app-django-d042bfeb04cb

[casbin-bot]

@seriouszyx @ComradeProgrammer @Resulte