Fix deprecated set-env action syntax for CI

[AlexNDRmac]

Hello!

• Type: code quality

Small description of change:

• Fixed deprecated set-env syntax for GitHub actions

Thanks

[codecov]

Codecov Report

Merging #95 (6eef9bf) into development (479fd30) will decrease coverage by 5.70%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           development      #95      +/-   ##
===============================================
- Coverage        80.80%   75.09%   -5.71%     
===============================================
  Files                7        5       -2     
  Lines             8912     2891    -6021     
===============================================
- Hits              7201     2171    -5030     
+ Misses            1711      720     -991     

Flag	Coverage Δ
unittests	75.09% <ø> (-5.71%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
parser/scanner.c
parser/zephir.c
zephir_parser.c	96.87% <0.00%> (+31.25%)	⬆️

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