add bandit to pep8 job

Add the bandit security scanner to the pep8 job.

Change-Id: I7b01e7edde84fb6c6860724c933b1dd70306c666

test-requirements.txt

@@ -15,3 +15,6 @@ testscenarios>=0.4 # Apache-2.0/BSD
 oslo.config>=4.6.0 # Apache-2.0
 
 reno>=2.5.0 # 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_i18n -x tests -n5
 
 [testenv:venv]
 commands = {posargs}