Bump katex from 0.16.19 to 0.16.21

Bumps [katex](https://github.com/KaTeX/KaTeX) from 0.16.19 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/v0.16.19...v0.16.21)

---
updated-dependencies:
- dependency-name: katex
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -38,7 +38,7 @@
     "chart.js": "^4.4.7",
     "fuse.js": "^7.0.0",
     "jquery": "^3.7.1",
-    "katex": "^0.16.19",
+    "katex": "^0.16.21",
     "lite-youtube-embed": "^0.3.3",
     "mermaid": "^11.4.1",
     "packery": "^2.1.2",