ci: update setup-go and checkout to latest action versions

[AlexCuse]

This should resolve node deprecation warnings when viewing action results in the github UI.

[codecov[bot]]

Codecov Report

Merging #406 (7200293) into master (d20a605) will decrease coverage by 0.14%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #406      +/-   ##
==========================================
- Coverage   76.69%   76.56%   -0.14%     
==========================================
  Files          57       57              
  Lines        3012     3012              
==========================================
- Hits         2310     2306       -4     
- Misses        563      566       +3     
- Partials      139      140       +1     

see 1 file with indirect coverage changes

[roblaszczak]

Thanks @AlexCuse!