Bump postcss from 8.5.3 to 8.5.6

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.6
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

package-lock.json

@@ -83,7 +83,7 @@
     "dotenv": "^16.4.5",
     "gh-pages": "^6.1.1",
     "lighthouse": "^12.2.2",
-    "postcss": "^8.4.47",
+    "postcss": "^8.5.6",
     "tailwindcss": "^3.4.12"
   },
   "browserslist": {