Add support for actions variables

[FedeDP]

https://docs.github.com/en/rest/actions/variables

Fixes #2624

• Added actions_variables.go
• Added actions_variables_test.go

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[gmlewis]

Thank you, @FedeDP!
It looks great and with a few minor tweaks we should be ready for a second LGTM+Approval before merging.

[codecov]

Codecov Report

Merging #2652 (ac3a7b4) into master (8eac70f) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2652      +/-   ##
==========================================
+ Coverage   98.08%   98.10%   +0.02%     
==========================================
  Files         130      131       +1     
  Lines       11304    11442     +138     
==========================================
+ Hits        11087    11225     +138     
  Misses        148      148              
  Partials       69       69              

Impacted Files	Coverage Δ
github/actions_variables.go	100.00% <100.00%> (ø)

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[FedeDP]

Should've fixed everything ;) Thank you!

[gmlewis]

Thank you, @FedeDP !
LGTM.

Awaiting second LGTM+Approval from any other contributor to this repo before merging.

[valbeat]

LGTM!

[FedeDP]

I merged master into this branch.

[gmlewis]

LGTM!

Thank you, @valbeat !
Merging.