Set hydrate return type to void instead of null

Author: TomHAnderson

src/Hydrator/Strategy/NullifyOwningAssociation.php

@@ -43,8 +43,7 @@ public function extract(mixed $value, object|null $object = null): mixed
      *
      * @codeCoverageIgnore
      */
-    public function hydrate(mixed $value, array|null $data): null
+    public function hydrate(mixed $value, array|null $data): void
     {
-        return null;
     }
 }