fix(alchemy-notice): Use default font size for headings

[tvdeyen]

What is this pull request for?

We do not want to mix font-sizes in notices. H1 was already resetted. H2 and H3 were missing.

Checklist

• I have followed Pull Request guidelines
• I have added a detailed description into each commit message
• I have added tests to cover this change

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.06%. Comparing base (53eecba) to head (c4b34ab).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3833   +/-   ##
=======================================
  Coverage   98.06%   98.06%           
=======================================
  Files         322      322           
  Lines        8526     8526           
=======================================
  Hits         8361     8361           
  Misses        165      165           

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[alchemycms-bot]

💔 Some backports could not be created

Status	Branch	Result
❌	8.0-stable	Backport failed because of merge conflicts
❌	8.1-stable	Backport failed because of merge conflicts
✅	8.2-stable

Manual backport

To create the backport manually run:

backport --pr 3833

Questions ?

Please refer to the Backport tool documentation and see the Github Action logs for details