fix: downgrade to codecov/codecov-action@v4.0.0

[Desiki-high]

Relevant Issue (if applicable)

N/A.

Details

codecov/codecov-action@v4 is unstable. ref codecov/codecov-action#1425

Types of changes

What types of changes does your PullRequest introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation Update (if none of the other choices apply)

Checklist

Go over all the following points, and put an x in all the boxes that apply.

• I have updated the documentation accordingly.
• I have added tests to cover my changes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.51%. Comparing base (e926d2f) to head (20bc47b).
Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1583      +/-   ##
==========================================
+ Coverage   61.23%   61.51%   +0.27%     
==========================================
  Files         144      144              
  Lines       47100    46616     -484     
  Branches    44602    44602              
==========================================
- Hits        28843    28676     -167     
+ Misses      16778    16456     -322     
- Partials     1479     1484       +5     

see 18 files with indirect coverage changes