Bump html-proofer from 3.17.1 to 3.17.2

Bumps html-proofer from 3.17.1 to 3.17.2.

Commits

• 3192c96 💎 bump to 3.17.2
• 943cc7b Merge pull request #597 from gjtorikian/oh-oh-broken-internals
• a774714 I guess these are all suggestions
• c05791c like this?
• 59c77f0 Merge pull request #599 from gjtorikian/switch-to-actions
• 5306637 Bye Travis
• c7f87fb Try adding CI
• 15bf0da explain myself
• 6636e5e Fix internal link handling for dirs w/o root_dir
• 2a44ea1 Merge pull request #596 from olleolleolle/patch-1
• Additional commits viewable in compare view