[release] 0.12.0 🎉

[eonu]

Major changes

• Rework preprocessing module (see #177). (#179)
  • Add Custom transformation.
  • Rename Preprocess to Compose.
  • Don't validate observation sequences after each transformation in Compose.
  • Remove progress bars and verbose parameter.
  • Stop unnecessarily copying each observation sequence before transformations.
  • Change transform() function on Transform objects to accept a single observation sequence.
  • Remove _apply() function on Transform objects.
  • Make _is_fitted() public on Transform objects (change to is_fitted()).
  • Use __str__ instead of _describe() for transformation descriptions.
• Remove need to send DeepGRU to device explicitly, so we can now do DeepGRU(..., device=device) instead of DeepGRU(..., device=device).to(device). (#178)
• Add dev, test, docs and notebooks extras. (#174)
• Remove Equalize transform as it goes against the point of variable-length sequence classification. (#172)
• Change TrimZeros transform to TrimConstants, allowing any constant-valued observation to be trimmed. (#172)
• Add DeepGRU classifier implementation. (#169)
• Add sequentia[torch] extra for optional torch CPU installation. (#169)

Minor changes

• Keep batch lengths on CPU (pytorch/pytorch#43227). (#178)
• Remove docs/requirements.txt and specify docs extra in .readthedocs.yml. (#176)
• Move Sphinx extensions from docs/conf.py to requirements.py. (#176)
• Bump development status classifier to beta. (#175)
• Move package dependency specifications to requirements.py. (#174)
• Add docs/README.md, notebooks/README.md and lib/test/README.md. (#174)
• Update HMM classifier diagram. (#173)
• Add build status to README.md. (#171)
• Fix patch description in CONTRIBUTING.md. (#170)
• Fix wording in README.md. (#167, #168)