Update to pytorch 2.0

Breaking Changes

• Upgraded to pytorch 2.0 and lightning 2.0. This brings a couple of changes, such as configuration of trainers. See the lightning upgrade guide. For PyTorch Forecasting, this particularly means if you are developing own models, the class method epoch_end has been renamed to on_epoch_end and replacing model.summarize() with ModelSummary(model, max_depth=-1) and Tuner(trainer) is its own class, so trainer.tuner needs replacing. (#1280)
• Changed the predict() interface returning named tuple - see tutorials.

Changes

• The predict method is now using the lightning predict functionality and allows writing results to disk (#1280).

Fixed

• Fixed robust scaler when quantiles are 0.0, and 1.0, i.e. minimum and maximum (#1142)