remove: postcss configuration

Author: winverse

apps/web/.postcssrc.back.json

@@ -42,8 +42,6 @@
     "inquirer": "^9.2.7",
     "nanoid": "^5.0.7",
     "next": "^14.2.1",
-    "postcss-flexbugs-fixes": "^5.0.2",
-    "postcss-preset-env": "^8.5.0",
     "prismjs": "^1.29.0",
     "react": "^18.2.0",
     "react-dom": "18.2.0",