Bump katex from 0.16.10 to 0.16.21 in /web (#1481)

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](KaTeX/KaTeX@v0.16.10...v0.16.21)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: carlobortolan <[email protected]>

Author: dependabot[bot]

web/package-lock.json

@@ -42,7 +42,7 @@
     "handlebars-loader": "^1.7.3",
     "http-status-codes": "^2.3.0",
     "ical.js": "^1.5.0",
-    "katex": "^0.16.10",
+    "katex": "^0.16.21",
     "mini-css-extract-plugin": "^2.7.6",
     "moment": "^2.30.1",
     "nouislider": "^15.7.1",