Upgrade GitHub actions

[andy128k]

• Bump MSRV to 1.54.0 to support macos 12 (XCode 14).
• Replace unsupported action-rs/* actions by alternatives.

[codecov]

Codecov Report

Merging #69 (ca35cbd) into master (eb33b90) will decrease coverage by 7.33%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #69      +/-   ##
==========================================
- Coverage   83.17%   75.84%   -7.34%     
==========================================
  Files          19       14       -5     
  Lines        1486     1010     -476     
==========================================
- Hits         1236      766     -470     
+ Misses        250      244       -6     

Impacted Files	Coverage Δ
src/util.rs	63.82% <0.00%> (-4.60%)	⬇️
src/content.rs	86.11% <0.00%> (-2.69%)	⬇️
src/feed.rs	80.90% <0.00%> (-1.59%)	⬇️
tests/read.rs
tests/write.rs
tests/content.rs
tests/text.rs
tests/builders.rs

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