Bump rehype-slug from 4.0.1 to 5.0.1

Bumps [rehype-slug](https://github.com/rehypejs/rehype-slug) from 4.0.1 to 5.0.1.
- [Release notes](https://github.com/rehypejs/rehype-slug/releases)
- [Commits](rehypejs/rehype-slug@4.0.1...5.0.1)

---
updated-dependencies:
- dependency-name: rehype-slug
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

package.json

@@ -39,7 +39,7 @@
 		"prismjs": "^1.26.0",
 		"pug": "^3.0.2",
 		"rehype-autolink-headings": "^5.1.0",
-		"rehype-slug": "^4.0.1",
+		"rehype-slug": "^5.0.1",
 		"remark-abbr": "^1.4.1",
 		"remark-github": "^10.1.0",
 		"sass": "^1.47.0",