Property name 'full_name' should be spelled 'fullname' without underscores

Hello,

I believe there is a spelling error at the file auth_backends/backends.py, line 12

I think it should be written 'fullname' without underscores, and not 'full_name'.

This is used for mapping the claims provided in the JWT returned by the OAuth authorization code grant flow, but the name 'full_name' is not recognized at the 'registration' part of the pipeline, which in turn leaves the corresponding registration field empty, making it impossible to proceed with a SSO without the user confirming the registration form (in the case it's the first time a user gets registered in by means of third party SSO).

Changing it into 'fullname' makes this work.

Tested using a production environment using the "auth_backends.backends.EdXOAuth2" backend used for SSO of LMS with a custom OAuth2 identity provider.

I don't know if it was the original purpose, but I found this implementation to be very useful to be used for SSO with a generic third party OAuth2 Identity Provider implemented in house (not one of those well known public providers already listed in python-social-auth).

Start at auth_backends/backends.py line 12 and inspect how the JWT claim is mapped into the registration data. Confirm the spelling used by the registration pipeline and verify that the corrected name populates the registration field so first-time SSO users can proceed without confirming the form.