Initial release that matches `pip_install lean_transformer==0.3.1` [on PyPI](https://pypi.org/project/lean-transformer/0.3.1/)
- LeanTransformer supports standard transformer architecture with optional rotary embeddings, gating, various normalization types
- Memory-efficeint backward, various parameter sharing strategies, adapters, checkpoints, reversible layers, sparsity
- LeanGPT* and LeanAlbert* models