Athreading

Added

* Added contributing document.

Changed

* Updated release workflow process.
* Updated Readme
* Test dependencies audited.

Added<!--0.2.0-->

* Added support for python 3.13 with free threading.
* Added support for python 3.9 with nogil.
* Added support for providing explicit background executor to decorators.
* Added call and iterate benchmarks.

Changed<!--0.2.0-->

* Changed `call`, `iterate` and `generate` to higher-order-function decorators.

Added<!--0.1.1-->

* Added `call`, `iterate` and `generate` functions.
* Added call benchmarks.