chore: Fix missing codecov report in PRs

[eps1lon]

What:

Fixes missing codecov reports in PRs

Why:

These are required for PRs to be mergable. Right now only admins can merge.

How:

Set fetch-depth to 0 as suggested

I also changed the action so that it fails CI on failure. Otherwise it's not obvious why the check is missing.

Added flags while we're at it to know where coverage might be missing.

Checklist:

• [ ] Documentation added to the
  docs site
• Tests (once we get the check)
• [ ] Typescript definitions updated
• Ready to be merged
  

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[codecov]

Codecov Report

Merging #897 (eb6f844) into master (47e52d1) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #897   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           26        26           
  Lines          941       941           
  Branches       283       283           
=========================================
  Hits           941       941           

Flag	Coverage Δ
node-10.14.2	100.00% <ø> (?)
node-12	100.00% <ø> (?)
node-14	100.00% <ø> (?)
node-15	100.00% <ø> (?)

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[github-actions]

🎉 This PR is included in version 7.29.6 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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