Update codecov uploader

[p4checo]

Checklist

• I've rebased my changes on top of master
• I've built and run the project to see all new and existing tests pass
• I've followed the Mindera swift style guide
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.

Motivation and Context

• Codecov has deprecated the old bash script, so we need to update our CI to use the new uploader.

Description

• Migrate CI to use the new codecov uploader via GH action.

[codecov]

Codecov Report

Base: 95.05% // Head: 95.87% // Increases project coverage by +0.82% 🎉

Coverage data is based on head (7011757) compared to base (9cae850).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #259      +/-   ##
==========================================
+ Coverage   95.05%   95.87%   +0.82%     
==========================================
  Files         100      100              
  Lines        3376     4996    +1620     
==========================================
+ Hits         3209     4790    +1581     
- Misses        167      206      +39     

Impacted Files	Coverage Δ
Sources/Extensions/Foundation/Thread.swift	90.00% <0.00%> (-10.00%)	⬇️
Sources/AutoLayout/ViewProxy.swift	87.50% <0.00%> (-4.50%)	⬇️
Sources/DeepLinking/Route+TrieRouter.swift	90.82% <0.00%> (-0.96%)	⬇️
...urces/Network/Network+URLSessionNetworkStack.swift	95.53% <0.00%> (-0.62%)	⬇️
.../ItemFormat/Log+ItemFormat+GenericComponents.swift	95.78% <0.00%> (-0.37%)	⬇️
Sources/Utils/Box.swift	100.00% <0.00%> (ø)
Sources/Logging/Log.swift	100.00% <0.00%> (ø)
Sources/Utils/Token.swift	100.00% <0.00%> (ø)
Sources/Network/HTTP.swift	100.00% <0.00%> (ø)
Sources/Shared/Retry.swift	100.00% <0.00%> (ø)
... and 90 more

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