make data provider static

Author: xabbuh

Tests/OptionsResolverTest.php

@@ -2068,7 +2068,7 @@ public function testDeeplyNestedUnionTypesException(string $type, $invalidValue,
         $this->resolver->resolve(['option' => $invalidValue]);
     }
 
-    public function provideValidDeeplyNestedUnionTypes(): array
+    public static function provideValidDeeplyNestedUnionTypes(): array
     {
         $resource = fopen('php://memory', 'r');
         $object = new \stdClass();
@@ -2144,7 +2144,7 @@ public function provideValidDeeplyNestedUnionTypes(): array
         ];
     }
 
-    public function provideInvalidDeeplyNestedUnionTypes(): array
+    public static function provideInvalidDeeplyNestedUnionTypes(): array
     {
         $resource = fopen('php://memory', 'r');
         $object = new \stdClass();