build(package.json): cleanup package step

removed sourcemaps and switched prepare to prepack

Author: TimoBechtel

package.json

@@ -8,9 +8,9 @@
   "unpkg": "dist/index.umd.js",
   "types": "dist/index.d.ts",
   "scripts": {
-    "build": "microbundle",
+    "build": "microbundle --no-sourcemap",
     "dev": "microbundle watch",
-    "prepare": "npm run build",
+    "prepack": "npm run build",
     "test": "npm run build && node test/index.test.js"
   },
   "files": [