Update to CommonMark 0.31.2

[MihaZupan]

Main changes:

• Definition of "Unicode punctuation character" has changed to also include symbol categories.
  • We were using the same helper when parsing autolinks (<http://...>) and GFM autolinks (http://...)
  • The one for AutoLinks seems to have been wrong, updated it to match the spec now
  • GitHub appears to allow symbols in its autolinks (e.g. emoji in domain name), so I tried to match that by keeping the old behavior there
• More forms of inline raw HTML comments are allowed: <!-->, <!--->
• search is apparently an HTML tag now

[xoofx]

Amazing, thanks for the update! 🚀