README: Fix CI status badge

[okurz]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.70%. Comparing base (e7a8843) to head (cd0bf0f).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #73      +/-   ##
==========================================
+ Coverage   89.59%   89.70%   +0.11%     
==========================================
  Files          27       27              
  Lines         903      903              
  Branches      207      207              
==========================================
+ Hits          809      810       +1     
  Misses         21       21              
+ Partials       73       72       -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.