Bump webpack-merge from 4.2.1 to 4.2.2 in /js

Bumps [webpack-merge](https://github.com/survivejs/webpack-merge) from 4.2.1 to 4.2.2.
- [Release notes](https://github.com/survivejs/webpack-merge/releases)
- [Changelog](https://github.com/survivejs/webpack-merge/blob/master/CHANGELOG.md)
- [Commits](https://github.com/survivejs/webpack-merge/compare/v4.2.1...v4.2.2)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

js/package.json

@@ -42,7 +42,7 @@
     "vue-template-compiler": "^2.6.10",
     "webpack": "^4.39.2",
     "webpack-cli": "^3.3.7",
-    "webpack-merge": "^4.2.1"
+    "webpack-merge": "^4.2.2"
   },
   "scripts": {
     "build": "NODE_ENV=production ./node_modules/webpack-cli/bin/cli.js --mode production --config webpack.prod.config.js",