CI: Allow codecov policies to fail.

[lemmih]

Summary of changes
Changes introduced in this pull request:

• PRs aren't blocked anymore if they contain code not covered by tests.

Reference issue to close (if applicable)

Other information and links

[codecov]

Codecov Report

Merging #1471 (3c8050e) into main (c54baa2) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1471   +/-   ##
=======================================
  Coverage   26.24%   26.24%           
=======================================
  Files         312      312           
  Lines       23788    23788           
=======================================
  Hits         6244     6244           
  Misses      17544    17544           

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