pyproject.toml:

* update supported python versions upto 3.13
* add waitress and bjoern as platform dependent deps
* add entry-point
* add project urls
* set explicit flat layout structure
* add package data
* add optional dep `docs`

`__main__.py`:
* add main function
* call main function from entrypoint and with direct execution

swingmusic/__main__.py

@@ -108,7 +108,10 @@ def run(*args, **kwargs):
     start_swingmusic(kwargs["host"], kwargs["port"])
 
 
-if __name__ == "__main__":
+def main():
     multiprocessing.freeze_support()
     multiprocessing.set_start_method("spawn")
     run()
+
+if __name__ == "__main__":
+    main()