add composer-merge-plugin

composer.json

@@ -13,6 +13,10 @@
     "config": {
         "platform": {
             "php": "8.2"
+        },
+        "allow-plugins": {
+            "composer/package-versions-deprecated": true,
+            "wikimedia/composer-merge-plugin": true
         }
     },
     "require": {
@@ -55,7 +59,6 @@
         "dmore/chrome-mink-driver": "2.8.0",
         "friendsofphp/php-cs-fixer": "3.1.0",
         "phpunit/phpunit": "9.5.9",
-        "sebastian/phpcpd": "6.0.3",
         "squizlabs/php_codesniffer": "3.6.0",
         "phpstan/phpstan": "^2.1"
     },
@@ -95,5 +98,19 @@
                 "symlink": false
             }
         }
-    ]
+    ],
+    "extra": {
+        "merge-plugin": {
+            "include": [
+                "composer.local.json"
+            ],
+            "recurse": true,
+            "replace": true,
+            "ignore-duplicates": false,
+            "merge-dev": true,
+            "merge-extra": false,
+            "merge-extra-deep": false,
+            "merge-scripts": true
+        }
+    }
 }