Merge branch '6.3' into 6.4

* 6.3:
  minor #53524 [Messenger] [AmazonSqs] Allow `async-aws/sqs` version 2 (smoench)
  Fix bad merge
  List CS fix in .git-blame-ignore-revs
  Fix implicitly-required parameters
  List CS fix in .git-blame-ignore-revs
  Apply php-cs-fixer fix --rules nullable_type_declaration_for_default_null_value

GenericRuntime.php

@@ -83,7 +83,7 @@ public function __construct(array $options = [])
         $this->options = $options;
     }
 
-    public function getResolver(callable $callable, \ReflectionFunction $reflector = null): ResolverInterface
+    public function getResolver(callable $callable, ?\ReflectionFunction $reflector = null): ResolverInterface
     {
         $callable = $callable(...);
         $parameters = ($reflector ?? new \ReflectionFunction($callable))->getParameters();

RuntimeInterface.php

@@ -23,7 +23,7 @@ interface RuntimeInterface
      *
      * The callable itself should return an object that represents the application to pass to the getRunner() method.
      */
-    public function getResolver(callable $callable, \ReflectionFunction $reflector = null): ResolverInterface;
+    public function getResolver(callable $callable, ?\ReflectionFunction $reflector = null): ResolverInterface;
 
     /**
      * Returns a callable that knows how to run the passed object and that returns its exit status as int.