Fix test

Author: ondrejmirtes

tests/PHPStan/Reflection/SignatureMap/Php8SignatureMapProviderTest.php

@@ -206,7 +206,7 @@ public function dataMethods(): array
 						'variadic' => false,
 					],
 				],
-				new UnionType([
+				new BenevolentUnionType([
 					new ObjectType('Closure'),
 					new NullType(),
 				]),