retired Haxe 3 compilation support

[AlexHaxe]

updated haxeparser, tokentree, json2object and munit libs

[codecov]

Codecov Report

Merging #502 (1b4dd94) into dev (1a13453) will decrease coverage by 0.63%.
The diff coverage is 58.33%.

@@            Coverage Diff             @@
##              dev     #502      +/-   ##
==========================================
- Coverage   95.17%   94.54%   -0.64%     
==========================================
  Files         106      106              
  Lines        7277     7223      -54     
  Branches      816      920     +104     
==========================================
- Hits         6926     6829      -97     
- Misses        351      359       +8     
- Partials        0       35      +35     

Impacted Files	Coverage Δ
src/checkstyle/CheckerThread.hx	93.42% <ø> (ø)
...kstyle/checks/block/ConditionalCompilationCheck.hx	100.00% <ø> (ø)
src/checkstyle/checks/block/EmptyBlockCheck.hx	92.18% <ø> (ø)
src/checkstyle/checks/block/LeftCurlyCheck.hx	95.32% <ø> (ø)
src/checkstyle/checks/block/NeedBracesCheck.hx	95.16% <ø> (ø)
src/checkstyle/checks/block/RightCurlyCheck.hx	98.93% <ø> (ø)
...rc/checkstyle/checks/coding/CodeSimilarityCheck.hx	98.80% <ø> (ø)
src/checkstyle/checks/coding/MagicNumberCheck.hx	96.66% <ø> (-0.21%)	⬇️
...checkstyle/checks/coding/NullableParameterCheck.hx	100.00% <ø> (ø)
...style/checks/coding/VariableInitialisationCheck.hx	100.00% <ø> (ø)
... and 32 more

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