Bump markdown-it-footnote from 3.0.3 to 4.0.0 (sass#902)

Bumps [markdown-it-footnote](https://github.com/markdown-it/markdown-it-footnote) from 3.0.3 to 4.0.0.
- [Changelog](https://github.com/markdown-it/markdown-it-footnote/blob/master/CHANGELOG.md)
- [Commits](markdown-it/markdown-it-footnote@3.0.3...4.0.0)

---
updated-dependencies:
- dependency-name: markdown-it-footnote
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

package.json

@@ -84,7 +84,7 @@
     "markdown-it-anchor": "^8.6.7",
     "markdown-it-attrs": "^4.1.6",
     "markdown-it-deflist": "^2.1.0",
-    "markdown-it-footnote": "^3.0.3",
+    "markdown-it-footnote": "^4.0.0",
     "netlify-plugin-11ty": "^1.4.0",
     "npm-run-all": "^4.1.5",
     "prettier": "^3.0.3",