Fixed type hints for CosineAnnealingWarmRestarts (#102067)
Fixed type hints for CosineAnnealingWarmRestarts:
- `T_mult` is not `Optional[int]` but just `int`
- `eta_min` is not `Optional[float]` but just `float`
- removed `step` method specific annotation as it is compatible with the base class
https://github.com/pytorch/pytorch/blob/e132f09e8878418fb98a4b76a441a324452354ec/torch/optim/lr_scheduler.py#L1365-L1375
Otherwise, computation like this `self.T_i * self.T_mult` in `self.step` is not possible:
```
error: Unsupported operand types for * ("int" and "None")
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/102067
Approved by: https://github.com/janeyx99
