Fix document publishing GitHub Action

[tautschnig]

mermaid-filter depends on a deprecated version of puppeteer, which
results in puppeteer no longer finding a suitable version of Chromium.
See puppeteer/puppeteer#9533 for others facing
this issue. Forcing npm to use the most recent release of puppeteer
(version 21) resolves this problem.

We should revert the workflow to one that doesn't text-insert a
dependency and just directly npm installs mermaid-filter once
mermaid-js/mermaid-cli#627 has been resolved,
a new release of mermaid-cli been produced, and mermaid-filter having
picked up that new release.

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (78a90e0) 79.09% compared to head (71d3b4e) 79.09%.
Report is 2 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8152   +/-   ##
========================================
  Coverage    79.09%   79.09%           
========================================
  Files         1695     1695           
  Lines       196578   196578           
========================================
  Hits        155488   155488           
  Misses       41090    41090           

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