Generate stubs for WPGraphQL v2.6.0

Author: github-actions[bot]

source/composer.json

@@ -13,7 +13,7 @@
     "ext-mbstring": "*",
     "ext-openssl": "*",
     "ext-sodium": "*",
-    "wpackagist-plugin/wp-graphql": "2.5.4"
+    "wpackagist-plugin/wp-graphql": "2.6.0"
   },
   "config": {
     "allow-plugins": {