chore: bump angular to v21

[cipchk]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 75.40984% with 15 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (master@529cec6). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
lib/src/highlight-js.ts	75.40%	12 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master      #33   +/-   ##
=========================================
  Coverage          ?   75.80%           
=========================================
  Files             ?        2           
  Lines             ?       62           
  Branches          ?       20           
=========================================
  Hits              ?       47           
  Misses            ?       12           
  Partials          ?        3           

Flag	Coverage Δ
unittests	75.80% <75.40%> (?)

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