fix: use OIDC for Codecov

[ThirdEyeSqueegee]

Issue #, if available:

Description of changes:
Code coverage broke due to GitHub separating repository secrets from Dependabot secrets. Use the OIDC token to write code coverage data to Codecov.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.52%. Comparing base (befeea6) to head (347e03e).
⚠️ Report is 7 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #180   +/-   ##
=======================================
  Coverage   72.52%   72.52%           
=======================================
  Files           6        6           
  Lines         222      222           
  Branches       23       23           
=======================================
  Hits          161      161           
  Misses         52       52           
  Partials        9        9           

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