Update return typehint for SchemaBuilder

Author: kix

src/Definition/Builder/SchemaBuilder.php

@@ -23,7 +23,7 @@ public function __construct(TypeResolver $typeResolver, bool $enableValidation =
         $this->enableValidation = $enableValidation;
     }
 
-    public function getBuilder(string $name, ?string $queryAlias, ?string $mutationAlias = null, ?string $subscriptionAlias = null, array $types = []): callable
+    public function getBuilder(string $name, ?string $queryAlias, ?string $mutationAlias = null, ?string $subscriptionAlias = null, array $types = []): \Closure
     {
         return function () use ($name, $queryAlias, $mutationAlias, $subscriptionAlias, $types): ExtensibleSchema {
             static $schema = null;

src/Request/Executor.php

@@ -57,7 +57,7 @@ public function setExecutor(ExecutorInterface $executor): self
         return $this;
     }
 
-    public function addSchemaBuilder(string $name, callable $builder): self
+    public function addSchemaBuilder(string $name, \Closure $builder): self
     {
         $this->schemas[$name] = $builder;