flake8 : ignore .cache subdirectory, avoid broken ansible-compat

This role pulls in zuul-jobs/system-config, etc. for roles into
.cache.  We don't want to flake8 them as part of this job; ignore the
.cache subdir.

This also avoids a broken release of ansible-compat per the linked bug
(I'm assuming the next version will fix it, so optimistically not
using <)

Change-Id: I5cf3029e40fcc0e02ba4d104beb59a1c75509a77

test-requirements.txt

@@ -8,4 +8,6 @@ hacking>=4.0.0,<5.0.0 # Apache-2.0
 ansible>=5,<6
 # pin until https://github.com/ansible/ansible-lint/issues/2320 is fixed
 ansible-lint>=6,<6.5
+# avoid for https://github.com/ansible/ansible-compat/issues/258
+ansible-compat!=4.0.1
 bashate>=0.2

tox.ini

@@ -44,4 +44,4 @@ commands = {posargs}
 # please don't submit patches that solely correct them or enable them.
 ignore = E125,E129,H
 show-source = True
-exclude = .venv,.tox,dist,doc,build,*.egg
+exclude = .venv,.tox,dist,doc,build,*.egg,.cache