build(deps-dev): bump rehype-slug from 5.1.0 to 6.0.0

Bumps [rehype-slug](https://github.com/rehypejs/rehype-slug) from 5.1.0 to 6.0.0.
- [Release notes](https://github.com/rehypejs/rehype-slug/releases)
- [Commits](rehypejs/rehype-slug@5.1.0...6.0.0)

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

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

Author: dependabot[bot]

package.json

@@ -51,7 +51,7 @@
     "mdast-util-toc": "^7.0.0",
     "rehype-autolink-headings": "^6.1.1",
     "rehype-pretty-code": "^0.10.1",
-    "rehype-slug": "^5.1.0",
+    "rehype-slug": "^6.0.0",
     "remark": "^14.0.3",
     "remark-code-import": "^1.2.0",
     "remark-gfm": "^3.0.1",