v0.6.1: fix: a few things (#52)

* fix: Semaphore len edge case

* fix: _loop is None in recent Python vers

* fix: another conflict with recent python

* chore: add more info to debug loggers

* feat: Event.loop convenience method to get loop in later py versions

* feat: settable Event debugger interval

* fix: Event for python 3.10+

* chore: cleanup PrioritySemaphore __repr__

* fix: PrioritySemaphore _wake_up_next

* fix: PrioritySemaphore _wake_up_next

* fix: define locked method for PrioritySemaphore

* fix: define acquire and release methods for DummySemaphore