Blacklist bandit 1.6.0

There's a regression[0] in bandit 1.6.0 which causes bandit to stop
respecting excluded directories, and our tests throw a bunch of
violations. Blacklist this version, but allow newer versions as there is
already a pull request[1] to fix it, and I expect it will be included in
the next release.

[0] https://github.com/PyCQA/bandit/issues/488
[1] https://github.com/PyCQA/bandit/pull/489

Change-Id: I4429614a57fb512fe2bfdf0686c3eff0adc2a2f4

doc/requirements.txt

@@ -4,4 +4,5 @@
 doc8>=0.6.0 # Apache-2.0
 openstackdocstheme>=1.18.1 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
-sphinx!=1.6.6,>=1.6.2 # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4' # BSD

test-requirements.txt

@@ -1,7 +1,7 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
-bandit>=1.1.0 # Apache-2.0
+bandit!=1.6.0,>=1.1.0 # Apache-2.0
 bashate>=0.5.1 # Apache-2.0
 beautifulsoup4>=4.6.0 # MIT
 coverage!=4.4,>=4.0 # Apache-2.0