Blacklist eventlet 0.23.0, 0.25.0
Blacklist eventlet 0.23.0, 0.25.0

Kombu 4.6.4 causes issues with eventlet 0.23.0 and 0.25.0[1].
Due to an upper-constraint version bump, we're seeing failures
on openstack gate.
This patch fixes the issue.

[1] https://review.opendev.org/#/c/678078

Change-Id: Ibec126bba7991f22611b476449e760d4faf5b8e8

openstack/monasca-api,openstack/monasca-api,stackforge/monasca-api,stackforge/monasca-api,openstack/monasca-api,stackforge/monasca-api,stackforge/monasca-api