Installation trips an error on non-macOS platforms because of indirect dependency on pyobjc-core

[thejohnfreeman]

Installing this package on non-macOS platforms prints this error:

An error occurred when reading setup.py or setup.cfg: 'Attribute' object has no attribute 'id'

Which is caused by this issue in pyobjc-core, which watchdog depends on through these paths:

watchdog -> pyobjc-framework-FSEvents -> pyobjc-core
watchdog -> pyobjc-framework-Cocoa -> pyobjc-core

Overall installation still succeeds, unless installing on Windows with $ErrorActionPreference = "Stop".

[BoboTiG]

This will be fixed by #642. Thanks for the report :)