Bump @tiptap/extension-highlight from 2.1.7 to 2.1.8

Bumps [@tiptap/extension-highlight](https://github.com/ueberdosis/tiptap/tree/HEAD/packages/extension-highlight) from 2.1.7 to 2.1.8.
- [Release notes](https://github.com/ueberdosis/tiptap/releases)
- [Changelog](https://github.com/ueberdosis/tiptap/blob/v2.1.8/packages/extension-highlight/CHANGELOG.md)
- [Commits](https://github.com/ueberdosis/tiptap/commits/v2.1.8/packages/extension-highlight)

---
updated-dependencies:
- dependency-name: "@tiptap/extension-highlight"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

package.json

@@ -31,7 +31,7 @@
         "vitest": "^0.34.3"
     },
     "dependencies": {
-        "@tiptap/extension-highlight": "^2.0.3",
+        "@tiptap/extension-highlight": "^2.1.8",
         "@tiptap/extension-image": "^2.0.3",
         "@tiptap/extension-link": "^2.0.3",
         "@tiptap/extension-subscript": "^2.0.3",