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

Author: renovate[bot]

apps/docs/package.json

@@ -55,7 +55,7 @@
     "eslint-config-next": "12.3.1",
     "eslint-config-prettier": "8.5.0",
     "gray-matter": "4.0.3",
-    "postcss": "8.4.18",
+    "postcss": "8.4.31",
     "prisma": "^4.7.1",
     "tailwindcss": "3.1.8",
     "typescript": "4.8.4"