chore: deprecate github api baseUrl

[andypols]

Summary

This PR addresses issue #1213

The github api baseUrl is not used in the codebase.

"api": {
    "github": {
      "baseUrl": "https://api.github.com"
    }
  },

Fix

It marks the github baseUrl as deprecated in the schema.

[netlify]

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[kriswest]

Added a commit to fix a failing test and tighten the schema a hair more

[kriswest]

...and another as the gitleaks config wasn't in the schema and additionalProperties: false started rejecting it

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.20%. Comparing base (292ecad) to head (3556da4).
⚠️ Report is 12 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1232   +/-   ##
=======================================
  Coverage   84.20%   84.20%           
=======================================
  Files          68       68           
  Lines        2938     2938           
  Branches      374      374           
=======================================
  Hits         2474     2474           
  Misses        404      404           
  Partials       60       60           

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[jescalada]

LGTM, I don't see any issues 🙂