Update rector.php

Co-authored-by: Adrien Dupuis <[email protected]>

Author: mnocon

rector.php

@@ -25,4 +25,5 @@
         SymfonySetList::SYMFONY_70,
         SymfonySetList::SYMFONY_71,
         SymfonySetList::SYMFONY_72,
+        SymfonySetList::SYMFONY_73,
     ]);