add bandit to pep8 job

Add the bandit security scanner to the pep8 job.

Change-Id: Ib4707b55c190b117410212cef7f5afc789c91583

test-requirements.txt

@@ -12,3 +12,5 @@ testtools>=2.2.0 # MIT
 coverage!=4.4,>=4.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 oslo.serialization!=2.19.1,>=2.18.0 # Apache-2.0
+# Bandit security code scanner
+bandit>=1.1.0 # Apache-2.0

tox.ini

@@ -12,7 +12,12 @@ deps = -r{toxinidir}/test-requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:pep8]
-commands = flake8
+deps =
+  -r{toxinidir}/test-requirements.txt
+commands =
+  flake8
+  # Run security linter
+  bandit -r oslo_middleware -x tests -n5
 
 [testenv:venv]
 commands = {posargs}