bug: Allow UsageError exception to use more specific error code UsageError exception returned 400 error code but should return 405 when generated for a bad http method. Modified error handler to use 400 error code if self.response_code was less then 400. This should reproduce the standard error of 400 if one was not specified and preserve any other explicitly set response code. Also enhanced a test case to verify the 405 is returned.

# 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()