feat(deps): upgrade webonyx/graphql-php to version 15.6.2

Author: dadish

composer.json

@@ -11,7 +11,7 @@
   ],
   "require": {
     "php": "^7.4||^8.0",
-    "webonyx/graphql-php": "^15.4.0"
+    "webonyx/graphql-php": "^15.6.2"
   },
   "require-dev": {
     "processwire/processwire": "dev-dev",