Bump Codecov action to 1.0.13

[dsk1306]

This might help to resolve an issue with uploading code coverage results to Codecov

bash codecov.sh -n CombineExt -F  -y 
codecov.sh: illegal option -- y
Unexpected flag not supported

Codevcov has failed to upload the report in my other PR.

[codecov]

Codecov Report

Merging #56 into master will decrease coverage by 1.39%.
The diff coverage is 86.51%.

@@            Coverage Diff             @@
##           master      #56      +/-   ##
==========================================
- Coverage   97.77%   96.37%   -1.40%     
==========================================
  Files          46       52       +6     
  Lines        2515     2871     +356     
==========================================
+ Hits         2459     2767     +308     
- Misses         56      104      +48     

Impacted Files	Coverage Δ
Sources/Convenience/Optional.swift	100.00% <ø> (ø)
Sources/Operators/PrefixDuration.swift	100.00% <ø> (ø)
Sources/Operators/Internal/Timer.swift	69.07% <69.07%> (ø)
Sources/Operators/Internal/Lock.swift	83.33% <83.33%> (ø)
Sources/Operators/MergeMany.swift	100.00% <100.00%> (ø)
Sources/Operators/Nwise.swift	100.00% <100.00%> (ø)
Tests/MergeManyTests.swift	100.00% <100.00%> (ø)
Tests/NwiseTests.swift	100.00% <100.00%> (ø)
... and 4 more

---

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[dsk1306]

@freak4pc

[freak4pc]

nice, thanks!