Update webpack-merge requirement from 4.2.1 to 4.2.2

Updates the requirements on [webpack-merge](https://github.com/survivejs/webpack-merge) to permit the latest version.
- [Release notes](https://github.com/survivejs/webpack-merge/releases)
- [Changelog](https://github.com/survivejs/webpack-merge/blob/master/CHANGELOG.md)
- [Commits](survivejs/webpack-merge@v4.2.1...v4.2.2)

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

Author: dependabot-preview[bot]

package.json

@@ -72,6 +72,6 @@
     "webpack": "4.29.6",
     "webpack-cli": "3.3.0",
     "webpack-dev-server": "3.11.0",
-    "webpack-merge": "4.2.1"
+    "webpack-merge": "4.2.2"
   }
 }