Revert "add customCSS support"

Author: parthlambdatest

package.json

@@ -43,7 +43,6 @@
     "json-stringify-safe": "^5.0.1",
     "listr2": "^7.0.1",
     "node-cache": "^5.1.2",
-    "postcss": "^8.5.6",
     "sharp": "^0.33.4",
     "tsup": "^7.2.0",
     "uuid": "^11.0.3",