Google One Tap implementation

[kviktor]

Proposed changes

The changes adds Google One Tap as a backend

Checklist

• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added documentation to https://github.com/python-social-auth/social-docs

Other information

You can test the changes with this dummy project https://github.com/kviktor/django-onetap-example

I haven't yet added tests or documentation but if the changes look okay I'll add them too.

I have 2 questions tho I'm not exactly sure about, maybe someone can help out

• I've added google-auth as a dependency, technically it's just downloading Google's cert files then verifying the jwt token however I didn't want to reimplement the wheel for it and it's a bit safer this way imo
• as it requires a new dependency I've added a new Python module for it, is that ok? (I can move it into google.py with catching ImportError and raising an exception if the library is missing in the class)

Docs at python-social-auth/social-docs#256

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.15%. Comparing base (326d4b3) to head (b828e46).
Report is 73 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1015      +/-   ##
==========================================
+ Coverage   77.88%   78.15%   +0.26%     
==========================================
  Files         347      348       +1     
  Lines       10669    10765      +96     
  Branches      504      457      -47     
==========================================
+ Hits         8310     8413     +103     
+ Misses       2200     2192       -8     
- Partials      159      160       +1     

Flag	Coverage Δ
unittests	78.15% <100.00%> (+0.26%)	⬆️

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[nijel]

Looks okay at first look. Can you please add tests and documentation?

[kviktor]

@nijel I've added some tests, because it's not on oauth flow they are a bit different.

Also added docs at python-social-auth/social-docs#256

Also switched from urllib3 to requests as I've just noticed this library already depends on it and that requirement doesn't need that weird packaging library workaround.

[nijel]

Merged, thanks for your contribution!