chore(deps): update dependency postcss to v8.4.26

Author: renovate[bot]

package-lock.json

@@ -26,7 +26,7 @@
     "eslint": "8.12.0",
     "eslint-config-next": "12.1.4",
     "next-sitemap": "2.5.20",
-    "postcss": "8.4.16",
+    "postcss": "8.4.26",
     "prettier": "2.6.2",
     "tailwindcss": "3.0.23",
     "typescript": "4.6.3"