Fix broken tempest-tox-plugin-sanity-check job

tempest-tox-plugin-sanity-check job is broken due to
'x/networking-cisco failing plugin. Plugin is brokken
after the below change
- https://review.opendev.org/c/x/networking-cisco/+/969038

Fixing the job by blacklist the 'x/networking-cisco plugin.

Change-Id: I156d3a682f697c6d0ad37451aacfd99816d89bc7
Signed-off-by: Ghanshyam Maan <gmaan.os14@gmail.com>
1 file changed