chore: it doesn't make sense to have a main field at the current stage

Author: haoqunjiang

package.json

@@ -3,7 +3,6 @@
   "version": "3.0.0-beta.4",
   "description": "An easy way to start a Vue project",
   "type": "module",
-  "main": "index.js",
   "bin": {
     "create-vue": "outfile.cjs"
   },