add scope repo for oauth with Github

[SimonLab]

ref: #182

This PR add manually the "repo" scope which gives read/write access to repository when using oauth token.

[codecov]

Codecov Report

Merging #184 (6d5c372) into main (e121667) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main      #184   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           27        27           
  Lines          586       586           
=========================================
  Hits           586       586           

Impacted Files	Coverage Δ
lib/auth_web/controllers/auth_controller.ex	100.00% <100.00%> (ø)

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[nelsonic]

@SimonLab this scope is only desirable for the labels App. We don't need it for our Main app. 💭

[SimonLab]

Indeed this is not a perfect solution as it changed the scope for all the applications created with auth.
I'll add checkboxes in the UI when creating a new app to select which scope to add