chore(deps-dev): bump clean-css-cli from 5.6.2 to 5.6.3

Bumps [clean-css-cli](https://github.com/clean-css/clean-css-cli) from 5.6.2 to 5.6.3.
- [Changelog](https://github.com/clean-css/clean-css-cli/blob/master/History.md)
- [Commits](clean-css/clean-css-cli@v5.6.2...v5.6.3)

---
updated-dependencies:
- dependency-name: clean-css-cli
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

package.json

@@ -39,7 +39,7 @@
 		"@traptitech/markdown-it-spoiler": "^1.1.6",
 		"chalk": "4.1.2",
 		"cheerio": "^1.0.0-rc.12",
-		"clean-css-cli": "^5.6.2",
+		"clean-css-cli": "^5.6.3",
 		"cross-spawn": "^7.0.3",
 		"eleventy-plugin-git-commit-date": "^0.1.3",
 		"eleventy-plugin-toc": "^1.1.5",