chore(deps): bump sanity-plugin-markdown from 2.1.1 to 3.0.1

Bumps [sanity-plugin-markdown](https://github.com/sanity-io/sanity-plugin-markdown) from 2.1.1 to 3.0.1.
- [Release notes](https://github.com/sanity-io/sanity-plugin-markdown/releases)
- [Changelog](https://github.com/sanity-io/sanity-plugin-markdown/blob/main/CHANGELOG.md)
- [Commits](https://github.com/sanity-io/sanity-plugin-markdown/compare/v2.1.1...v3.0.1)

---
updated-dependencies:
- dependency-name: sanity-plugin-markdown
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

sites/sanity/package.json

@@ -37,7 +37,7 @@
     "prop-types": "^15.7",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
-    "sanity-plugin-markdown": "^2.1.1",
+    "sanity-plugin-markdown": "^3.0.1",
     "styled-components": "^5.2.0"
   },
   "devDependencies": {