No significant changes.
- Require Python 3.8 or later.
#1: doctest on check() uses pytest instead of pip for
broader compatibility.
check() now raises an Unresolved exception, an iterable
indicating the unresolved dependencies.
Added missing() method to generate missing dependencies for
an EntryPoint.
Added backward compatibility for EntryPoint objects as found in older importlib metadata implementations.
Experimental initial implementation. Supplies check function
for checking an ep for validity.