celery-heimdall

• Remove a pinned dependency, which was to work around a bug in importlib-metadata that prevent celery from being imported.
• Relax all other required dependencies to wildcard versions, as we work with all known versions, and all projects that depend on us would have overlapping dependencies.

• Try to acquire lock at runtime, not just on apply_sync(), which works around issues with send_task() and celery beat not even using apply_sync().
• Supports str instead of lambda for task key.

Add support for providing rate limits based off the function key, task, args, and/or kwargs.

• Added a new only_after helper.
• Fix a dependency issue on Python 3.7 caused by the 5.0.0 release of importlib-metadata (https://github.com/python/importlib_metadata/issues/411)

Added support (enabled by default) for "silent" unique tasks, which will simply return the existing tasks's AsyncResult instead of raising an exception, making it fairly transparent.

It's alive! First working version