Python-anvil

- Fixed optional field `CreateEtchPacket.signature_email_subject` being required. This is now truly optional.
- Added support for `CreateEtchPacket.signature_email_body`.
- Added support for `CreateEtchPacket.replyToName` and `CreateEtchPacket.replyToEmail` which customizes the "Reply-To"
header in Etch packet emails.

- Fixed issue with Etch packet `is_test` and `is_draft` options not properly applying to the final GraphQL mutation when
using `CreateEtchPacket.create_payload`.

- Added `py.typed` for better mypy support.
- Updated a number of dev dependencies.

- Added support for `webhook_url` on Etch packets. Please see the `CreateEtchPacketPayload` class
and [Anvil API docs](https://www.useanvil.com/docs/api/e-signatures#webhook-notifications) for more info.
- Better support for extra (unsupported) fields in all models. Previously fields not defined in models would be
stripped, or would raise a runtime error. Additional fields will no longer be stripped and will be used in JSON
payloads as you may expect. Note that, though this is now supported, the Anvil API will return an error for any
unsupported fields.
- Updated documentation.

Merged

- Return all errors that come from the server [`3`](https://github.com/anvilco/node-anvil/pull/3)
- Bo readme changes [`2`](https://github.com/anvilco/node-anvil/pull/2)
- Few suggestions [`1`](https://github.com/anvilco/node-anvil/pull/1)

Commits

- Initial [`186d2f1`](https://github.com/anvilco/node-anvil/commit/186d2f1258a335687fd40a77fa08600c4f2633ba)
- Add initial client and cli example [`09a2873`](https://github.com/anvilco/node-anvil/commit/09a28733142597a0fb4ef13dd8fdbeee50c55c43)
- Add test:watch command [`7f07f15`](https://github.com/anvilco/node-anvil/commit/7f07f15521df392655976d51b9378c1b6c3e6837)

- **[BREAKING CHANGE]** `dataclasses-json` library removed and replaced
with [pydantic](https://github.com/samuelcolvin/pydantic/).
This should not affect any users who only use the CLI and API methods, but if you are using any models directly
from `api_resources/payload.py`, you will likely need to update all usages. Please
see [pydantic's docs](https://pydantic-docs.helpmanual.io/usage/models/) for more details.
- **[BREAKING CHANGE]** Increased minimum required Python version to 3.6.2.
- Updated `EtchSigner` model to be more in sync with new official documentation.
See `create_etch_existing_cast.py` file for examples and `api_resources/payload.py` for `EtchSigner` changes.
- Updated CLI command `anvil cast --list` to only return casts that are templates.
Use `anvil cast --all` if you'd like the previous behavior.
- Updated a number of dependencies, the vast majority being dev-dependencies.