Update dependency webpack-merge to v6

Author: renovate[bot]

package-lock.json

@@ -36,7 +36,7 @@
     "style-loader": "3.3.4",
     "webpack": "5.90.3",
     "webpack-cli": "5.1.4",
-    "webpack-merge": "5.10.0"
+    "webpack-merge": "6.0.1"
   },
   "dependencies": {
     "cross-env": "^7.0.3",