Ariadne

- Remove `ariadne.contrib.django` from release.
- Lock `GraphQL-core` requirement at <3.2.

- Added `on_connect` and `on_disconnect` options to `ariadne.asgi.GraphQL`, enabling developers to run additional initialization and cleanup for websocket connections.
- Updated Starlette dependency to 0.17.1.
- Added support for multiple keys for GraphQL federations.
- Made `Query` type optional in federated schemas.
- Updated default resolvers to test for `Mapping` instead of `dict`.
- Removed `ariadne.contrib.django`. (Use [ariadne_django](https://github.com/reset-button/ariadne_django) instead).
- Updated query cost validator to handle optional variables.

- Updated `graphql-core` requirement to 3.1.3.
- Added support for Python 3.9.
- Added support for using nested variables as cost multipliers in the query price validator.
- `None` is now correctly returned instead of `{"__typename": typename}` within federation.
- Fixed some surprising behaviors in `convert_kwargs_to_snake_case` and `snake_case_fallback_resolvers`.

- Added `validation_rules` option to query executors as well as ASGI and WSGI apps and Django view that allow developers to include custom query validation logic in their APIs.
- Added `introspection` option to ASGI and WSGI apps, allowing developers to disable GraphQL introspection on their server.
- Added `validation.cost_validator` query validator that allows developers to limit maximum allowed query cost/complexity.
- Removed default literal parser from `ScalarType` because GraphQL already provides one.
- Added `extensions` and `introspection` configuration options to Django view.
- Updated requirements list to require `graphql-core` 3.

- Fixed `convert_kwargs_to_snake_case` utility so it also converts the case in lists items.
- Removed support for sending queries and mutations via WebSocket.
- Freezed `graphql-core` dependency at version 3.0.3.
- Unified default `info.context` value for WSGI to be dict with single `request` key.

- Added support for `Apollo Federation`.
- Added the ability to send queries to the same channel as the subscription via WebSocket.