build(deps-dev): bump postcss from 8.4.39 to 8.4.40 in /frontend

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](https://github.com/postcss/postcss/compare/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] <support@github.com>

frontend/package-lock.json

@@ -65,7 +65,7 @@
         "eslint-plugin-matrix-org": "^1.2.1",
         "happy-dom": "^14.12.3",
         "i18next-parser": "^9.0.1",
-        "postcss": "^8.4.39",
+        "postcss": "^8.4.40",
         "postcss-modules": "^6.0.0",
         "postcss-nesting": "^12.1.5",
         "prettier": "3.3.2",
@@ -18216,9 +18216,9 @@
       }
     },
     "node_modules/postcss": {
-      "version": "8.4.39",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.39.tgz",
-      "integrity": "sha512-0vzE+lAiG7hZl1/9I8yzKLx3aR9Xbof3fBHKunvMfOCYAtMhrsnccJY2iTURb9EZd5+pLuiNV9/c/GZJOHsgIw==",
+      "version": "8.4.40",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.40.tgz",
+      "integrity": "sha512-YF2kKIUzAofPMpfH6hOi2cGnv/HrUlfucspc7pDyvv7kGdqXrfj8SCl/t8owkEgKEuu8ZcRjSOxFxVLqwChZ2Q==",
       "dev": true,
       "funding": [
         {

frontend/package.json

@@ -74,7 +74,7 @@
     "eslint-plugin-matrix-org": "^1.2.1",
     "happy-dom": "^14.12.3",
     "i18next-parser": "^9.0.1",
-    "postcss": "^8.4.39",
+    "postcss": "^8.4.40",
     "postcss-modules": "^6.0.0",
     "postcss-nesting": "^12.1.5",
     "prettier": "3.3.2",