Bump postcss from 8.4.17 to 8.4.18

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.17 to 8.4.18.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.17...8.4.18)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -12,7 +12,7 @@
     "cross-env": "^7.0.3",
     "rtlcss": "^4.0.0",
     "npm-run-all": "^4.1.5",
-    "postcss": "^8.4.17",
+    "postcss": "^8.4.18",
     "postcss-cli": "^10.0.0",
     "remark-cli": "^11.0.0",
     "remark-lint": "^9.1.1",