[improve][ci] Upgrade codecov-action version

[lhotari]

Motivation

In GitHub Actions workflows there's a warning about codecov-action@v3:

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: codecov/codecov-action@v3. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

Modifications

• upgrade codecov-action to v4

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.53%. Comparing base (1b1cfb5) to head (aa9bb0f).
Report is 4 commits behind head on master.

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #22123       +/-   ##
=============================================
+ Coverage     34.05%   73.53%   +39.48%     
- Complexity    12150    32065    +19915     
=============================================
  Files          1659     1874      +215     
  Lines        129418   139380     +9962     
  Branches      14173    15281     +1108     
=============================================
+ Hits          44079   102500    +58421     
+ Misses        79497    28940    -50557     
- Partials       5842     7940     +2098     

Flag	Coverage Δ
inttests	24.66% <ø> (-0.08%)	⬇️
systests	24.26% <ø> (?)
unittests	72.80% <ø> (+40.93%)	⬆️

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see 1513 files with indirect coverage changes