fix: Correctly tokenize YAML meta tags with non alphabetical characters after multiline string

[andrewnester]

Issue #, if available: #4694

Description of changes:
Correctly tokenize YAML meta tags with non alphabetical characters after multiline string

Previously match regex did not include non alphabetical characters in such meta tag keywords.

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[codecov]

Codecov Report

Merging #4706 (c117c3b) into master (d59c22b) will decrease coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4706      +/-   ##
==========================================
- Coverage   71.24%   71.19%   -0.06%     
==========================================
  Files         553      553              
  Lines       55598    55598              
  Branches    10392    10392              
==========================================
- Hits        39612    39584      -28     
- Misses      15986    16014      +28     

Flag	Coverage Δ
unittests	71.19% <ø> (-0.06%)	⬇️

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Impacted Files	Coverage Δ
lib/ace/mode/yaml_highlight_rules.js	86.84% <ø> (ø)
lib/ace/editor.js	79.64% <0.00%> (-1.98%)	⬇️

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