assert about min_segment_length in format_data

[Wenping-Cui]

Y, mask, metadata = batch(coordinates, seg_length=seg_length, keys=keys)
Y = Y.astype(float)
min_segment_length = np.diff(metadata[1], axis=1).min()
assert min_segment_length >= 4, ( f"The shortest segment has length  {min_segment_length} which is below the "
 "minimum of 4. Try increasing `seg_length` in the config (e.g. add "f"{min_segment_length} to its current value) and also make sure that all your ""input recordings are at least 4 frames long." )

jax_moseq.utils.batch would break up the data into fixed length segments. I found that it would report error when the number of frames happens to be seg_length+num<4. I would suggest to modify format_data to prune and filter out the short sequences within some threshold instead of reporting an error when min_segment_length<4 with assert.