Drop Windows event loop hack in Python 3.8+

In Python versions prior to 3.8, it appears that attempting to close the
event loop after a Ctrl-C would reliably hang the process, which would
need to be killed.

I've been unable to reproduce the behavior in any newer Python versions,
so I think it's time to set the timeline for removing the hack entirely.

This should take care of the common ResourceWarning messages when using
newer Python versions.

colcon_parallel_executor/executor/parallel.py

@@ -96,11 +96,13 @@ def execute(self, args, jobs, *, on_error=OnError.interrupt): # noqa: D102
  return 1
  finally:
  # HACK on Windows closing the event loop seems to hang after Ctrl-C
- # even though no futures are pending
- if sys.platform != 'win32':
+ # even though no futures are pending, but appears fixed in py3.8
+ if sys.platform != 'win32' or sys.version_info >= (3, 8):
  logger.debug('closing loop')
  loop.close()
  logger.debug('loop closed')
+ else:
+ logger.debug('skipping loop closure')
  result = future.result()
  logger.debug(
  "run_until_complete finished with '{result}'".format_map(locals()))

setup.cfg

@@ -55,8 +55,6 @@ filterwarnings =
  ignore:pkg_resources is deprecated as an API::flake8_import_order
  ignore:SelectableGroups dict interface is deprecated::flake8
  ignore:Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated::pyreadline
- # Suppress resource warnings pending investigation
- always::ResourceWarning
 junit_suite_name = colcon-parallel-executor
 
 [options.entry_points]