chore(deps): update dependency postcss to v8.5.6

Author: renovate[bot]

package.json

@@ -48,7 +48,7 @@
     "jest-image-snapshot": "6.4.0",
     "lint-staged": "15.3.0",
     "next-themes": "0.4.4",
-    "postcss": "8.5.0",
+    "postcss": "8.5.6",
     "postcss-loader": "8.1.1",
     "prettier": "3.6.2",
     "prettier-plugin-tailwindcss": "0.6.10",