chore: update go-github to use token

[aburan28]

Minor change here to load the token for the github client using the WIthAuthToken method instead of using the x oauth2 library. This simplifies this section of code and removes the oauth2 dependency.

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• The title of the PR conforms to the Toolchain Guide
• I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Does this PR require documentation updates?
• I've updated documentation as required by this PR.
• I have signed off all my commits as required by DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
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• My new feature complies with the feature status guidelines.
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• Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).

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[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 55.24%. Comparing base (f6a84a4) to head (da8695f).
Report is 22 commits behind head on master.

Files with missing lines	Patch %	Lines
applicationset/services/pull_request/github.go	66.66%	1 Missing ⚠️
applicationset/services/scm_provider/github.go	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #21292      +/-   ##
==========================================
- Coverage   55.25%   55.24%   -0.01%     
==========================================
  Files         337      337              
  Lines       56940    56825     -115     
==========================================
- Hits        31461    31395      -66     
+ Misses      22801    22740      -61     
- Partials     2678     2690      +12     

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[nitishfy]

LGTM, thanks!