Bump postcss from 8.4.39 to 8.4.40

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.39 to 8.4.40.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.39...8.4.40)

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

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

package.json

@@ -37,7 +37,7 @@
     "@web/test-runner": "^0.18.2",
     "eslint": "^8.57.0",
     "open-props": "^1.7.4",
-    "postcss": "^8.4.39",
+    "postcss": "^8.4.40",
     "postcss-cli": "^11.0.0",
     "postcss-import": "^16.1.0",
     "postcss-jit-props": "^1.0.14",