Bumps [katex](https://github.com/KaTeX/KaTeX) from 0.11.1 to 0.12.0.
- [Release notes](https://github.com/KaTeX/KaTeX/releases)
- [Changelog](https://github.com/KaTeX/KaTeX/blob/master/CHANGELOG.md)
- [Commits](https://github.com/KaTeX/KaTeX/compare/v0.11.1...v0.12.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>