Temporarily downgrade codecov-action to 5.0.3 to fix CI

[bdraco]

see codecov/codecov-action#1683

[codspeed-hq]

CodSpeed Performance Report

Merging #1425 will not alter performance

_{Comparing pin_code_cov_action (a54f91e) with master (a8d2556)}

Summary

✅ 85 untouched benchmarks

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.62%. Comparing base (a8d2556) to head (a54f91e).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1425      +/-   ##
==========================================
+ Coverage   96.06%   99.62%   +3.55%     
==========================================
  Files          31       23       -8     
  Lines        5774     4737    -1037     
  Branches      348      316      -32     
==========================================
- Hits         5547     4719     -828     
+ Misses        201       18     -183     
+ Partials       26        0      -26     

Flag	Coverage Δ
CI-GHA	99.55% <ø> (+3.48%)	⬆️
MyPy	?
OS-Linux	99.55% <ø> (ø)
OS-Windows	99.62% <ø> (ø)
OS-macOS	99.30% <ø> (ø)
Py-3.10.11	99.28% <ø> (ø)
Py-3.10.15	99.51% <ø> (ø)
Py-3.11.10	99.51% <ø> (ø)
Py-3.11.9	99.28% <ø> (ø)
Py-3.12.7	99.51% <ø> (ø)
Py-3.13.0	99.51% <ø> (ø)
Py-3.9.13	99.24% <ø> (ø)
Py-3.9.20	99.47% <ø> (ø)
Py-pypy7.3.16	99.53% <ø> (ø)
Py-pypy7.3.17	99.55% <ø> (ø)
VM-macos-latest	99.30% <ø> (ø)
VM-ubuntu-latest	99.55% <ø> (ø)
VM-windows-latest	99.62% <ø> (ø)
pytest	99.55% <ø> (ø)

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[bdraco]

We should remove the code-cov pin once codecov/codecov-action#1683 is solved