Update dependency webpack-merge to v6

Author: renovate[bot]

package-lock.json

@@ -57,7 +57,7 @@
         "webpack-bundle-analyzer": "4.10.2",
         "webpack-cli": "5.1.4",
         "webpack-dev-server": "4.15.2",
-        "webpack-merge": "5.10.0"
+        "webpack-merge": "6.0.1"
     },
     "dependencies": {
         "lodash": "4.17.21"