chore(ci): re-enable codecov

[bfabio]

Coverage is now at ~86% overall (95% on the main package).

Fix #329.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.36%. Comparing base (2f12edb) to head (5109ee4).
⚠️ Report is 14 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #350       +/-   ##
===========================================
+ Coverage   47.61%   84.36%   +36.75%     
===========================================
  Files          15       15               
  Lines        1067     1209      +142     
===========================================
+ Hits          508     1020      +512     
+ Misses        529      160      -369     
+ Partials       30       29        -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.