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.
• My build is green (troubleshooting builds).
• My new feature complies with the feature status guidelines.
• I have added a brief description of why this PR is necessary and/or what this PR solves.
• Optional. My organization is added to USERS.md.
• 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 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 55.19%. Comparing base (f15e1bc) to head (52f422a).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
applicationset/services/pull_request/github.go	50.00%	1 Missing ⚠️
applicationset/services/scm_provider/github.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #21292      +/-   ##
==========================================
- Coverage   55.23%   55.19%   -0.05%     
==========================================
  Files         337      337              
  Lines       57055    57043      -12     
==========================================
- Hits        31515    31483      -32     
- Misses      22847    22867      +20     
  Partials     2693     2693              

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