Bump markdown-it from 10.0.0 to 12.0.4

[dependabot]

Bumps markdown-it from 10.0.0 to 12.0.4.

Changelog

Sourced from markdown-it's changelog.

[12.0.4] - 2020-12-20

Fixed

• Fix crash introduced in 12.0.3 when processing strikethrough (~~) and similar plugins, #742.
• Avoid fenced token mutation, #745.

[12.0.3] - 2020-12-07

Fixed

• [](https://github.com/markdown-it/markdown-it/blob/master/<foo<bar>) is no longer a valid link.
• [](https://github.com/markdown-it/markdown-it/blob/master/url (xxx()) is no longer a valid link.
• [](https://github.com/markdown-it/markdown-it/blob/master/url\ xxx) is no longer a valid link.
• Fix performance issues when parsing links (#732, #734), backticks, (#733, #736), emphases (#735), and autolinks (#737).
• Allow newline in <? ... ?> in an inline context.
• Allow <meta> html tag to appear in an inline context.

[12.0.2] - 2020-10-23

Fixed

• Three pipes (|\n|\n|) are no longer rendered as a table with no columns, #724.

[12.0.1] - 2020-10-19

Fixed

• Fix tables inside lists indented with tabs, #721.

[12.0.0] - 2020-10-14

Added

• .gitattributes, force unix eol under windows, for development.

Changed

• Added 3rd argument to highlight(code, lang, attrs), #626.
• Rewrite tables according to latest GFM spec, #697.
• Use rollup.js to browserify sources.
• Drop bower.json (bower reached EOL).
• Deps bump.
• Tune specsplit.js options.
• Drop Makefile in favour of npm scrips.

Fixed

• Fix mappings for table rows (amended fix made in 11.0.1), #705.
• %25 is no longer decoded in beautified urls, #720.

[11.0.1] - 2020-09-14

Fixed

• Fix blockquote lazy newlines, #696.
• Fix missed mappings for table rows, #705.

... (truncated)

Commits

• 7b8969c 12.0.4 released
• 6f41c70 dist rebuild
• c9949dd Avoid fenced token mutation, #745
• be22253 Update funding info
• c9dd942 Fix crash when processing strikethrough
• ef59691 12.0.3 released
• 2710272 dist rebuild
• fc3dc00 Update pathological tests crc
• ddbb195 Remove meta from list of block html tags
• 8ad16ac Allow EOL in processing instructions
• Additional commits viewable in compare view

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[dependabot]

Looks like markdown-it is up-to-date now, so this is no longer needed.