Bump katex and markmap-lib

Bumps [katex](https://github.com/KaTeX/KaTeX) to 0.16.21 and updates ancestor dependency [markmap-lib](https://github.com/markmap/markmap). These dependencies need to be updated together.


Updates `katex` from 0.16.11 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@v0.16.11...v0.16.21)

Updates `markmap-lib` from 0.17.1 to 0.18.8
- [Release notes](https://github.com/markmap/markmap/releases)
- [Commits](markmap/markmap@v0.17.1...v0.18.8)

---
updated-dependencies:
- dependency-name: katex
  dependency-type: indirect
- dependency-name: markmap-lib
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -92,7 +92,7 @@
     "jsqr": "^1.4.0",
     "jstz": "^2.1.1",
     "leaflet": "^1.7.1",
-    "markmap-lib": "^0.17.0",
+    "markmap-lib": "^0.18.8",
     "markmap-view": "^0.17.0",
     "mermaid": "^10.9.3",
     "muicss": "^0.10.3",