feat(dependencies): minimal default tag install (#3362)

tests/training/test_visual_validation.py

@@ -31,6 +31,8 @@ from pathlib import Path
 import numpy as np
 import pytest
 
+pytest.importorskip("datasets", reason="datasets is required (install lerobot[dataset])")
+
 from lerobot.configs.default import DatasetConfig
 from lerobot.configs.policies import PreTrainedConfig
 from lerobot.configs.train import TrainPipelineConfig