Pymdown-extensions

- **NEW**: Experimental general purpose blocks.

- **FIX**: Snippets syntax can break in XML comments as XML comments do not allow `--`. Relax Snippets syntax such that
`-8<-` (single `-`) are allowed.

- **FIX**: Use a different CDN for Twemoji icons as MaxCDN is no longer available.

- **ENHANCE**: BetterEm: Further improvements to strong/emphasis handling:
- Ensure that one or more consecutive `*` or `_` surrounded by whitespace are not considered as a token.
- **ENHANCE**: Caret: Apply recent BetterEm improvements to Caret:
- Fix case where `^^` nested between `^` would be handled in an unexpected way.
- Ensure that one or more consecutive `^` surrounded by whitespace are not considered as a token.
- **ENHANCE**: Tilde: Apply recent BetterEm improvements to Tilde:
- Fix case where `~~` nested between `~` would be handled in an unexpected way.
- Ensure that one or more consecutive `~` surrounded by whitespace are not considered a token.
- **ENHANCE**: Mark: Apply recent BetterEm improvements to Mark:
- Ensure that one or more consecutive `=` surrounded by whitespace are not considered a token.

- **NEW**: Formally declare support for Python 3.11.
- **FIX**: BetterEm: Fix case where `**` nested between `*` would be handled in an unexpected way.

- **NEW**: Tabbed: Add new syntax to allow forcing a specific tab to be selected by default.
- **NEW**: Snippets: Add a new option to pass arbitrary HTTP headers.
- **NEW**: Snippets: Allow specifying sections in a snippet and including just the specified section.