fix prepack script

package.json

@@ -18,7 +18,7 @@
     "lint:js": "eslint .",
     "lint:js:fix": "eslint . --fix",
     "lint:sol": "solhint --max-warnings 0 \"contracts/**/*.sol\"",
-    "prepack": "npm run prepack",
+    "prepack": "scripts/prepack.sh",
     "release": "scripts/release/release.sh",
     "version": "scripts/release/update-changelog-release-date.js && scripts/release/update-ethpm-version.js",
     "test": "npm run compile && scripts/test.sh"