Spacy-transformers

* Extend transformers support to `<4.10.0`
* Enable pickling of span getters and annotation setters, which is required for multiprocessing with spawn

- Allow spaCy 3.1
- Extend transformers to <4.7.0

✨ New features and improvements

- Add support for transformers v4.3-v4.5
- Add extra for CUDA 11.2

🔴 Bug fixes

- Fix 264, 265: Improve handling of empty docs
- Fix 269: Add `trf_data` extension in `Transformer.__call__` and `Transformer.pipe` to support distributed processing

👥 Contributors

Thanks to bryant1410 for the pull requests and contributions!

🔴 Bug fixes

- Fix listener initialization when model width is unset.

> **This release requires [spaCy v3](https://nightly.spacy.io/usage/v3).**

✨ New features and improvements

- Rewrite library from scratch for spaCy v3.0.
- `Transformer` component for easy pipeline integration.
- `TransformerListener` to share transformer weights between components.
- Built-in registered functions that are available in spaCy if `spacy-transformers` is installed in the same environment.

📖 Documentation

- [Embeddings, Transformers and Transfer Learning](https://nightly.spacy.io/usage/embeddings-transformers): How to use transformers in spaCy
- [Training Pipelines and Models](https://nightly.spacy.io/usage/training):
Train and update components on your own data and integrate custom models
- [Layers and Model Architectures](https://nightly.spacy.io/usage/layers-architectures):
Power spaCy components with custom neural networks
- [`Transformer`](https://nightly.spacy.io/api/transformer): Pipeline component API reference
- [Transformer architectures](https://nightly.spacy.io/api/architectures#transformers): Architectures and registered functions

> 🌙 **This release is a pre-release and requires [spaCy v3](https://nightly.spacy.io/usage/v3) (nightly).**

✨ New features and improvements

- Add support for Python 3.9
- Add support for transformers v4

🔴 Bug fixes

- Fix 230: Add upstream argument to `TransformerListener.v1`
- Fix 238: Skip special tokens during alignment
- Fix 246: Raise error if model max length exceeded