Typehint created_at and updated_at values for phpstan (#1023)

Author: aSeriousDeveloper

src/Models/Audit.php

@@ -9,6 +9,8 @@
  * @property string $event
  * @property array<string,mixed> $new_values
  * @property array<string,mixed> $old_values
+ * @property Carbon|null $created_at
+ * @property Carbon|null $updated_at
  * @property mixed $user
  * @property mixed $auditable.
  */