Move CI to GitHub Actions

[sergeyklay]

Hello!

• Type: new feature
• Link to issue: -

In raising this pull request, I confirm the following:

• I have read and understood the Contributing Guidelines
• I have checked that another pull request for this purpose does not exist.
• I wrote some tests for this PR.

Small description of change:

• Move CI to GitHub Actions
• Cleaned up install-re2c.sh script
• Add macOS support

Thanks

[codecov]

Codecov Report

Merging #83 into development will increase coverage by 6.67%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           development      #83      +/-   ##
===============================================
+ Coverage        73.85%   80.52%   +6.67%     
===============================================
  Files                5        5              
  Lines             2719     6538    +3819     
===============================================
+ Hits              2008     5265    +3257     
- Misses             711     1273     +562

Flag	Coverage Δ
#unittests	80.52% <ø> (?)

Impacted Files	Coverage Δ
parser/scanner.re	86.75% <0%> (-11.51%)	⬇️
parser/parser.h	89.13% <0%> (-1.91%)	⬇️
parser/base.c	93.78% <0%> (+1.47%)	⬆️

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