Add functionality to HMM package to load and save HMMs from pickle files

[ncguilbeault]

Summary

This PR adds functionality to the Bonsai.ML.HiddenMarkovModels package to enable HMMs to be saved to and loaded from pickle files on disk.

Changes

• Fixed issue with loading and saving pickle object
• Added include workflow for loading from pkl
• Update package version to preview
• Update workflow to include quotes around string path
• Add custom unpickler to fix issue with missing module