Bump html-proofer from 3.18.0 to 3.18.3

Bumps html-proofer from 3.18.0 to 3.18.3.

Commits

• 84362d6 💎 bump to 3.18.3
• b7e39a5 Merge pull request #613 from tisba/allow-ruby-3-0
• 68f4cae limits ruby version to be < 4.0
• 575c6f5 allows Ruby 3.0 to be used
• 480c471 💎 bump to 3.18.2
• 4ec5831 Merge pull request #612 from gjtorikian/yet-another-broken-hash
• 8f8f0a4 All rubbish
• a555714 Expand the concept of internal
• 92e9d8c Rework this concat a bit
• 59d2344 Don't work like that
• Additional commits viewable in compare view