sktime-dl is currently being ported to mini-packages within sktime, and no longer maintained as a separate package.
Most estimators formerly in sktime-dl are now available in the sktime.classification.deep_learning and sktime.regression.deep_learning modules, and maintained there.
Contributions are appreciated to port the rest!
To contribute, follow instructions in the umbrella planning issue sktime/sktime#3351 on the sktime repo.