docs: update badge for CI workflow

[browniebroke]

Committed via https://github.com/asottile/all-repos

[codecov]

Codecov Report

Merging #739 (0729286) into main (7cf129a) will not change coverage.
The diff coverage is n/a.

❗ Current head 0729286 differs from pull request most recent head d95f970. Consider uploading reports for the commit d95f970 to get more accurate results

@@           Coverage Diff           @@
##             main     #739   +/-   ##
=======================================
  Coverage   98.73%   98.73%           
=======================================
  Files          30       30           
  Lines        1028     1028           
  Branches      221      221           
=======================================
  Hits         1015     1015           
  Partials       13       13           

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