use prepack to build packages

Author: Mahad-10

package.json

@@ -14,9 +14,7 @@
     "access": "public"
   },
   "scripts": {
-    "prepare": "npm run build",
-    "postinstall": "npm run postinstall:build",
-    "postinstall:build": "if [ ! -f ts-built/index.js ]; then npm run build; fi",
+    "prepack": "npm run build",
     "build": "rollup -c",
     "test": "NODE_OPTIONS=--experimental-vm-modules jest ./lib/* ./tests/*",
     "lint": "eslint . --ext .ts",