fix: update detection of changelog links (take 2)

[richardlau]

Underscores in the links to the changelogs are escaped for markdown
links but not escaped for HTML links.

Refs: #573
Refs: nodejs/node#40617

[codecov]

Codecov Report

Merging #575 (0482bb8) into main (44c6fc8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #575   +/-   ##
=======================================
  Coverage   82.57%   82.57%           
=======================================
  Files          35       35           
  Lines        1750     1750           
=======================================
  Hits         1445     1445           
  Misses        305      305           

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[Trott]

I'm contemplating seeing if remark-gfm can be changed so that it doesn't escape _ in these situations at all. It's unnecessary, I think.