add codecov token to merge and dev ci pipelines

[dennisbader]

Checklist before merging this PR:

• Mentioned all issues that this PR fixes or addresses.
• Summarized the updates of this PR under Summary.
• Added an entry under Unreleased in the Changelog.

Summary

• Fixes failing CI pipeline at Codecov upload step.
  • Codecov was added to Github apps since Access tokens (classic) have been disabled
  • Added codecov token secret to repository
  • CI now uses that token to authenticate

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.00%. Comparing base (5c97c9b) to head (5a35691).
Report is 7 commits behind head on master.

❗ Current head 5a35691 differs from pull request most recent head 3af7793. Consider uploading reports for the commit 3af7793 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2309      +/-   ##
==========================================
+ Coverage   93.96%   94.00%   +0.04%     
==========================================
  Files         137      138       +1     
  Lines       13971    14131     +160     
==========================================
+ Hits        13128    13284     +156     
- Misses        843      847       +4     

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