make data provider static

Author: xabbuh

src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/PhpFrameworkExtensionTest.php

@@ -267,7 +267,7 @@ public function testValidatorEmailValidationMode(string $mode)
         });
     }
 
-    public function emailValidationModeProvider()
+    public static function emailValidationModeProvider()
     {
         foreach (Email::VALIDATION_MODES as $mode) {
             yield [$mode];