Add doc/requirements

We need to specify doc requirements in doc/requirements.txt
to avoid problems with the pip resolver for the release team.
Removed specific doc requirements from test-requirements.txt

Change-Id: I8595eeadcbfd9c45949c676312fc4079795f9953

doc/requirements.txt

@@ -0,0 +1,3 @@
+reno>=3.1.0 # Apache-2.0
+sphinx>=2.0.0,!=2.1.0 # BSD
+openstackdocstheme>=2.2.1 # Apache-2.0

test-requirements.txt

@@ -8,8 +8,6 @@ coverage!=4.4,>=4.0 # Apache-2.0
 # used by libvirt driver
 libvirt-python>=6.0.0 # LGPLv2+
 python-subunit>=1.0.0 # Apache-2.0/BSD
-sphinx>=2.0.0,!=2.1.0 # BSD
-openstackdocstheme>=2.2.1 # Apache-2.0
 # used by nova driver
 openstacksdk>=0.13.0  # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
@@ -17,6 +15,5 @@ stestr>=1.0.0 # Apache-2.0
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT
 munch>=2.1.0 # MIT
-reno>=3.1.0 # Apache-2.0
 flake8-import-order>=0.17.1 # LGPLv3
 pycodestyle>=2.0.0,<2.7.0 # MIT

tox.ini

@@ -34,14 +34,18 @@ commands =
    coverage xml -o cover/coverage.xml
 
 [testenv:docs]
+deps = -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+       -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:pdf-docs]
 whitelist_externals = make
+deps = {[testenv:docs]deps}
 commands = sphinx-build -b latex doc/source doc/build/pdf
            make -C doc/build/pdf
 
 [testenv:releasenotes]
+deps = {[testenv:docs]deps}
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html