Features
* feat: Add support to custom attributes in User model before creation.
Use the `GITHUB_SSO_PRE_CREATE_CALLBACK` setting to define a custom function which can return a dictionary which will be used during user creation for the `defaults` value. ([`1ac0b47`](https://github.com/megalus/django-github-sso/commit/1ac0b47f0d457d2799cd4ad071ea871fea52fa65))