Fix DefinePlugin "Conflicting values for 'process.env'" warning

Author: linusg

vue.config.js

@@ -10,9 +10,7 @@ module.exports = {
   configureWebpack: {
     plugins: [
       new webpack.DefinePlugin({
-        "process.env": {
-          PACKAGE_VERSION: `"${version}"`,
-        },
+        "process.env.PACKAGE_VERSION": `"${version}"`,
       }),
       new MomentLocalesPlugin(),
     ],