CI: inherit secrets in coverage workflow

[ohmyfelix]

What changed

• Added secrets: inherit to .github/workflows/coverage.yml for the reusable coverage workflow call.

Why

• This rollout ensures the coverage workflow receives the required secrets when invoking the shared workflow, matching Roll out secrets: inherit for reusable coverage workflows contributte#74.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (master@4b6f34e). Learn more about missing BASE report.

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #406   +/-   ##
=========================================
  Coverage          ?   33.33%           
=========================================
  Files             ?        5           
  Lines             ?       42           
  Branches          ?        0           
=========================================
  Hits              ?       14           
  Misses            ?       28           
  Partials          ?        0           

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