No check for expired token

[paulw11]

The current code does not check for an expired access token.
PR #218 adds a check for this

[wagnerdelima]

Hi all.

My team and I are constantly using this framework and it seems it has died out there. I contacted the owner by email asking if he would add some of us as maintainers so we could continue to improve it. However we didn't get a response.

I am publishing the project under my profile and we are going to continue to invest time in it.

So I would like to gently ask you to contribute to this project on: https://github.com/wagnerdelima/drf-social-oauth2

Thank you for understanding.