feat: support github enterprise api

[ricardojdsilva87]

Pull Request

Proposed Changes

This Pull request is based on the already merged github/evergreen#256 to give support to GitHub Enterprise login using a GitHub App also created on GitHub Enterprise

Code coverage

---------- coverage: platform darwin, python 3.13.0-final-0 ----------
Name                 Stmts   Miss  Cover   Missing
--------------------------------------------------
auth.py                 16      1    94%   47
cleanowners.py          47      0   100%
env.py                  61      8    87%   41-42, 88-89, 100, 145, 155, 164
markdown_writer.py      10      0   100%
--------------------------------------------------
TOTAL                  134      9    93%

Required test coverage of 80% reached. Total coverage: 93.28%

Readiness Checklist

Author/Contributor

• If documentation is needed for this change, has that been included in this pull request
• run make lint and fix any issues that you have introduced
• run make test and ensure you have test coverage for the lines you are introducing
• If publishing new data to the public (scorecards, security scan results, code quality results, live dashboards, etc.), please request review from @jeffrey-luszcz

Reviewer

• Label as either fix, documentation, enhancement, infrastructure, maintenance or breaking

[jmeridth]

Please update .env-example also