Fix lower-constraints job

pip 20.3 finally includes a proper dependency resolver. Its use is
causing the following error messages on the lower-constraints job:

  ERROR: Cannot install ... because these package versions have
  conflicting dependencies.

  The conflict is caused by:
      bandit 1.1.0 depends on PyYAML>=3.1.0
      cliff 3.4.0 depends on PyYAML>=3.12
      openstacksdk 0.52.0 depends on PyYAML>=3.13

Bump our lower constraint for PyYAML to resolve this issue. With that
resolved, we see a new issue:

  ERROR: Could not find a version that satisfies the requirement
  cryptography>=2.7 (from openstacksdk)
  ERROR: No matching distribution found for cryptography>=2.7

This is less self-explanatory but looking at the lower-constraints for
openstacksdk 0.52.0 shows a dependency on cryptography 2.7 [1], meaning
we need to bump this also.

Next up, flake8-import-order seems to cause the dependency resolver to
go nuts, eventually ending with the following error message in a Python
3.6 environment:

  Using cached enum34-1.1.2.zip (49 kB)
    ERROR: Command errored out with exit status 1:
     command: ...
         cwd: ...
    Complete output (9 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File ".../lib/python3.6/site-packages/setuptools/__init__.py", line 7, in <module>
        import setuptools.distutils_patch  # noqa: F401
      File ".../lib/python3.6/site-packages/setuptools/distutils_patch.py", line 9, in <module>
        import re
      File "/usr/lib64/python3.6/re.py", line 142, in <module>
        class RegexFlag(enum.IntFlag):
    AttributeError: module 'enum' has no attribute 'IntFlag'
    ----------------------------------------

A quick Google suggests this is because the enum34 package is not
complete [2]. We shouldn't even be using it since our base virtualenv
should at least use Python 3.6, but I guess some dependency doesn't
properly restrict the dependency to <= Python 3.4. This is moved from
'test-requirements.txt' to 'tox.ini' since we don't need to use our
constraints machinery for linters.

Finally, the versions of bandit and hacking that pip is bringing in both
requires in a newer version of babel, which in turn requires a new
version of pytz.

  Collecting hacking>=2.0.0
  ...
  ERROR: Cannot install oslo.i18n because these package versions have
  conflicting dependencies.
  The conflict is caused by:
      babel 2.9.0 depends on pytz>=2015.7
      babel 2.8.1 depends on pytz>=2015.7
      babel 2.8.0 depends on pytz>=2015.7
      babel 2.7.0 depends on pytz>=2015.7

Seeing as we shouldn't be tracking bandit in
lower-constraints, I'm not sure why we're want to bump these
dependencies for just that. As above, we move these dependencies out of
'test-requirements' and into 'tox.ini' since we can do that for linters.

[1] https://opendev.org/openstack/openstacksdk/src/tag/0.52.0/requirements.txt#L19
[2] https://github.com/iterative/dvc/issues/1995#issuecomment-491889669

Change-Id: I8ec738fbcabc8d8553db79a876e5592576cd18fa
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>

lower-constraints.txt

@@ -9,7 +9,7 @@ cliff==3.4.0
 cmd2==0.8.0
 contextlib2==0.4.0
 coverage==4.0
-cryptography==2.1
+cryptography==2.7
 ddt==1.0.1
 debtcollector==1.2.0
 decorator==4.4.1
@@ -105,7 +105,7 @@ python-watcherclient==2.5.0
 python-zaqarclient==1.0.0
 python-zunclient==3.6.0
 pytz==2013.6
-PyYAML==3.12
+PyYAML==3.13
 repoze.lru==0.7
 requests-mock==1.2.0
 requests==2.14.2

test-requirements.txt

@@ -1,10 +1,8 @@
 # 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.
-hacking>=2.0.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
-flake8-import-order>=0.13 # LGPLv3
 oslotest>=3.2.0 # Apache-2.0
 requests>=2.14.2 # Apache-2.0
 requests-mock>=1.2.0 # Apache-2.0
@@ -12,6 +10,5 @@ stestr>=1.0.0 # Apache-2.0
 testtools>=2.2.0 # MIT
 tempest>=17.1.0 # Apache-2.0
 osprofiler>=1.4.0 # Apache-2.0
-bandit!=1.6.0,>=1.1.0 # Apache-2.0
 wrapt>=1.7.0 # BSD License
 ddt>=1.0.1 # MIT

tox.ini

@@ -28,9 +28,13 @@ commands =
   {toxinidir}/tools/fast8.sh
 
 [testenv:pep8]
+deps =
+  hacking>=2.0.0
+  bandit!=1.6.0,>=1.1.0
+  flake8-import-order>=0.13 # LGPLv3
 commands =
-    flake8
-    bandit -r openstackclient -x tests -s B105,B106,B107,B401,B404,B603,B606,B607,B110,B605,B101
+  flake8
+  bandit -r openstackclient -x tests -s B105,B106,B107,B401,B404,B603,B606,B607,B110,B605,B101
 
 [testenv:bandit]
 # This command runs the bandit security linter against the openstackclient