test: issue2551366. Probe for open port in test_liveserver.py Add a method to probe for an open port to wsgi_liveserver.py. Start the roundup server under wsgi on the open port. If a port can't be found, it skips all tests. Also changed all hardcoded URL references to use the dynamicly determined tracker url/port value. I fed my patch to wsgi_liveserver.py upstream at: https://github.com/jerrykan/wsgi-liveserver/issues/3

# https://issues.roundup-tracker.org/issue2551278
# datetime.utcnow deprecated
try:
    from datetime import UTC, datetime

    def utcnow():
        return datetime.now(UTC)

except ImportError:
    from datetime import datetime

    def utcnow():
        return datetime.utcnow()