mypy: make optimization module pass type checks (#1729)

src/lerobot/optim/optimizers.py

@@ -45,7 +45,7 @@ def default_choice_name(cls) -> str | None:
         return "adam"
 
     @abc.abstractmethod
-    def build(self) -> torch.optim.Optimizer | dict[str, torch.optim.Optimizer]:
+    def build(self, *args: Any, **kwargs: Any) -> torch.optim.Optimizer | dict[str, torch.optim.Optimizer]:
         """
         Build the optimizer. It can be a single optimizer or a dictionary of optimizers.
         NOTE: Multiple optimizers are useful when you have different models to optimize.

src/lerobot/optim/schedulers.py

@@ -30,7 +30,7 @@
 
 @dataclass
 class LRSchedulerConfig(draccus.ChoiceRegistry, abc.ABC):
-    num_warmup_steps: int
+    num_warmup_steps: int | None = None
 
     @property
     def type(self) -> str: