Speed up CI, add more checks (#115)

- Split pytest and end-to-end tests into separate jobs
- Add poetry check to ensure pyproject.toml and poetry.lock are in sync
- Add ruff format --diff to ensure style formatting is applied (fails if ruff would reformat anything)

lerobot/common/policies/act/modeling_act.py

@@ -195,7 +195,6 @@ class ActionChunkingTransformerPolicy(nn.Module):
 
         return loss_dict
 
-
     def _stack_images(self, batch: dict[str, Tensor]) -> dict[str, Tensor]:
         """Stacks all the images in a batch and puts them in a new key: "observation.images".