Adds missing "prepackage" script to build index.js before creating the zip file

Author: flesch

package.json

@@ -42,6 +42,7 @@
     "package": "node-lambda package --handler dist/index.default --configFile deploy.env --functionName $npm_package_name --excludeGlobs \"./index.js webpack.config.js context.json event.json .babelrc .nvmrc .gitignore LICENSE.md README.md\"",
     "postinstall": "node-lambda setup",
     "predeploy": "NODE_ENV=production webpack -p",
+    "prepackage": "NODE_ENV=production webpack -p",
     "pretest": "webpack",
     "setup": "node-lambda setup",
     "start": "webpack --watch",