Fix Huggingface datasets dependency compatibility issue (#561)

[cpa2001]

Description

Fixes the TypeError in compute_norm_stats.py caused by incompatibility with latest Huggingface datasets version 4.0.0.

Problem

• torch.stack(hf_dataset["timestamp"]) fails with TypeError when using datasets>=4.0.0
• hf_dataset["timestamp"] now returns a datasets.Column instead of tensor list/tuple
• This breaks the compute_norm_stats.py script

Solution

• Pin datasets==3.6.0 to maintain compatibility

Testing

• Verified compute_norm_stats.py runs successfully with pinned versions
• No breaking changes to existing functionality

Closes #561