chore(deps): bump markdown-it-footnote from 3.0.3 to 4.0.0

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:production
  update-type: version-update:semver-major
...

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

package.json

@@ -39,7 +39,7 @@
     "markdown-it-container": "^3.0.0",
     "markdown-it-deflist": "^2.0.3",
     "markdown-it-emoji": "^2.0.0",
-    "markdown-it-footnote": "^3.0.1",
+    "markdown-it-footnote": "^4.0.0",
     "markdown-it-ins": "^3.0.0",
     "markdown-it-mark": "^3.0.0",
     "markdown-it-sub": "^1.0.0",