chore(deps): update dependency postcss to v8.4.31 [security]

Author: renovate[bot]

package-lock.json

@@ -38,7 +38,7 @@
     "autoprefixer": "10.4.14",
     "eslint": "8.37.0",
     "eslint-config-next": "13.3.0",
-    "postcss": "8.4.21",
+    "postcss": "8.4.31",
     "prettier": "2.8.7",
     "prettier-plugin-tailwindcss": "0.2.7",
     "stylelint": "15.4.0",