Bump katex from 0.16.11 to 0.16.21 in /client

Bumps [katex](https://github.com/KaTeX/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)

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

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

client/package.json

@@ -72,7 +72,7 @@
     "eslint-plugin-jsx-a11y": "^6.8.0",
     "eslint-plugin-react": "^7.33.2",
     "jest-fetch-mock": "^3.0.3",
-    "katex": "^0.16.11",
+    "katex": "^0.16.21",
     "markdown-it-katex": "^2.0.3",
     "oidc-client-ts": "^3.0.1",
     "prop-types": "^15.8.1",

client/yarn.lock

@@ -7859,10 +7859,10 @@ jwt-decode@^4.0.0:
   resolved "https://registry.yarnpkg.com/jwt-decode/-/jwt-decode-4.0.0.tgz#2270352425fd413785b2faf11f6e755c5151bd4b"
   integrity sha512-+KJGIyHgkGuIq3IEBNftfhW/LfWhXUIY6OmyVWjliu5KH1y0fw7VQ8YndE2O4qZdMSd9SqbnC8GOcZEy0Om7sA==
 
-katex@^0.16.11:
-  version "0.16.11"
-  resolved "https://registry.yarnpkg.com/katex/-/katex-0.16.11.tgz#4bc84d5584f996abece5f01c6ad11304276a33f5"
-  integrity sha512-RQrI8rlHY92OLf3rho/Ts8i/XvjgguEjOkO1BEXcU3N8BqPpSzBNwV/G0Ukr+P/l3ivvJUE/Fa/CwbS6HesGNQ==
+katex@^0.16.21:
+  version "0.16.21"
+  resolved "https://registry.yarnpkg.com/katex/-/katex-0.16.21.tgz#8f63c659e931b210139691f2cc7bb35166b792a3"
+  integrity sha512-XvqR7FgOHtWupfMiigNzmh+MgUVmDGU2kXZm899ZkPfcuoPuFxyHmXsgATDpFZDAXCI8tvinaVcDo8PIIJSo4A==
   dependencies:
     commander "^8.3.0"