Bump markdown-it in /extensions/markdown-language-features (#18061)

Bumps [markdown-it](https://github.com/markdown-it/markdown-it) from 12.0.4 to 12.3.2.
- [Release notes](https://github.com/markdown-it/markdown-it/releases)
- [Changelog](https://github.com/markdown-it/markdown-it/blob/master/CHANGELOG.md)
- [Commits](https://github.com/markdown-it/markdown-it/compare/12.0.4...12.3.2)

---
updated-dependencies:
- dependency-name: markdown-it
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

extensions/markdown-language-features/package.json

@@ -354,7 +354,7 @@
   "dependencies": {
     "dompurify": "^2.3.1",
     "highlight.js": "^10.4.1",
-    "markdown-it": "^12.0.3",
+    "markdown-it": "^12.3.2",
     "markdown-it-front-matter": "^0.2.1",
     "vscode-extension-telemetry": "0.2.8",
     "vscode-nls": "^5.0.0"