build(deps): bump katex from 0.16.10 to 0.16.21
Bumps [katex](https://github.com/KaTeX/KaTeX) from 0.16.10 to 0.16.21.
- [Release notes](https://github.com/KaTeX/KaTeX/releases)
- [Changelog](https://github.com/KaTeX/KaTeX/blob/main/CHANGELOG.md)
- [Commits](https://github.com/KaTeX/KaTeX/compare/v0.16.10...v0.16.21)
---
updated-dependencies:
- dependency-name: katex
dependency-type: indirect
...
Signed-off-by: dependabot[bot] <[email protected]>