build(deps-dev): bump katex from 0.16.20 to 0.16.21

Bumps [katex](https://github.com/KaTeX/KaTeX) from 0.16.20 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@v0.16.20...v0.16.21)

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

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

package.json

@@ -55,7 +55,7 @@
     "highlight.js": "^11.11.1",
     "hugo-installer": "^4.0.1",
     "instant.page": "^5.2.0",
-    "katex": "^0.16.20",
+    "katex": "^0.16.21",
     "lazysizes": "^5.3.2",
     "markdownlint-cli2": "^0.10.0",
     "netlify-plugin-submit-sitemap": "^0.4.0",