Build(deps): Update wikimedia/composer-merge-plugin requirement

Updates the requirements on wikimedia/composer-merge-plugin to permit the latest version.

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

Author: dependabot-preview[bot]

.build/composer.json

@@ -4,7 +4,7 @@
     "prefer-stable": true,
     "require": {
         "narrowspark/coding-standard": "^5.1.0",
-        "wikimedia/composer-merge-plugin": "^1.4.1"
+        "wikimedia/composer-merge-plugin": "^2.0.1"
     },
     "extra": {
         "merge-plugin": {