[stable-only] Cap bandit to 1.6.2

The 1.6.3 [1] release has dropped support for py2 [2] so cap to 1.6.2
when using py2.

swift-multinode-rolling-upgrade is also made non-voting in order for
this change to land as we cannot deploy from stable/train without this
change.

[1] https://github.com/PyCQA/bandit/releases/tag/1.6.3
[2] PyCQA/bandit#615

Depends-On: https://review.opendev.org/c/openstack/devstack/+/768256
Depends-On: https://review.opendev.org/c/openstack/devstack/+/768257
Closes-Bug: #1907438
Change-Id: I294d5350e2f418614e54ff7bdd47dff16bfdcdbc

.zuul.yaml

@@ -553,6 +553,7 @@
               # Keep doc/manpages -- we want to syntax check them
               - ^doc/(requirements.txt|(saio|s3api|source)/.*)$
         - swift-multinode-rolling-upgrade:
+            voting: false
             irrelevant-files:
               - ^(api-ref|doc|releasenotes)/.*$
               - ^test/probe/.*$

test-requirements.txt

@@ -22,6 +22,6 @@ fixtures>=3.0.0 # Apache-2.0/BSD
 keystonemiddleware>=4.17.0 # Apache-2.0
 
 # Security checks
-bandit>=1.1.0 # Apache-2.0
+bandit>=1.1.0,<=1.6.2 # Apache-2.0
 
 docutils>=0.11  # OSI-Approved Open Source, Public Domain