Added
- Added a `MockBroker` for internal testing.
- Added more tests to the `app` module.
- Added a `prelude` module.
- Added support for YAML, MsgPack, and Pickle content types, behind the `extra_content_types` feature flag.
Changed
- Improved `TaskResultExt`. Now takes a `FnOnce() -> Context` instead of `&str`.
Fixed
- Ensure a `Signature` inherits default `TaskOptions` from the corresponding `Task` and `Celery` or `Beat` app.
- Cleaned up remaining uses of `.unwrap()` in the library.
- Options returned with `Task::options()` now have the current values, where app-level values are overridden by task-level values.