[Tests] Remove $this occurrences in future static data providers

Author: alexandre-daubois

Tests/EventListener/ErrorListenerTest.php

@@ -209,7 +209,7 @@ public function controllerProvider()
         }];
 
         yield [function ($exception) {
-            $this->assertInstanceOf(FlattenException::class, $exception);
+            static::assertInstanceOf(FlattenException::class, $exception);
 
             return new Response('OK: '.$exception->getMessage());
         }];