Move pep8 dependencies from test-requirements to tox.ini

They're not needed there and are hard to constraint properly.

Change-Id: I2d9dee3dc2299656f305559145f7801b25ef30f3

test-requirements.txt

@@ -1,10 +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.
-hacking>=3.1.0,<4.0.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
-doc8>=0.6.0 # Apache-2.0
-flake8-import-order>=0.17.1 # LGPLv3
 fixtures>=3.0.0 # Apache-2.0/BSD
 requests-mock>=1.2.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
@@ -13,6 +10,3 @@ tempest>=17.1.0 # Apache-2.0
 stestr>=1.0.0 # Apache-2.0
 ddt>=1.0.1 # MIT
 python-openstackclient>=3.12.0 # Apache-2.0
-pycodestyle>=2.0.0,<2.7.0 # MIT
-# Required for syntax highlighting check
-Pygments>=2.2.0 # BSD

tox.ini

@@ -27,6 +27,12 @@ deps =
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:pep8]
+deps =
+    hacking>=3.1.0,<4.0.0 # Apache-2.0
+    doc8>=0.6.0 # Apache-2.0
+    flake8-import-order>=0.17.1 # LGPLv3
+    pycodestyle>=2.0.0,<2.7.0 # MIT
+    Pygments>=2.2.0 # BSD
 commands =
     flake8 {posargs}
     doc8 doc/source CONTRIBUTING.rst README.rst