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: Ibeb6253046787a7a0768879067facaaeb0137cdb

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

@@ -7,9 +7,4 @@ hacking>=3.1.0,<4.0.0 # Apache-2.0
 flake8-import-order>=0.17.1 # LGPLv3
 # documentation
 doc8>=0.6.0 # Apache-2.0
-sphinx>=2.0.0,!=2.1.0 # BSD
-openstackdocstheme>=2.2.1 # Apache-2.0
 pycodestyle>=2.0.0,<2.7.0 # MIT
-
-# releasenotes
-reno>=3.1.0 # Apache-2.0

tox.ini

@@ -23,14 +23,21 @@ commands =
 commands = {posargs}
 
 [testenv:docs]
+usedevelop = False
+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]
+usedevelop = False
 whitelist_externals = make
+deps = {[testenv:docs]deps}
 commands = sphinx-build -b latex doc/source doc/build/pdf
            make -C doc/build/pdf
 
 [testenv:releasenotes]
+usedevelop = False
+deps = {[testenv:docs]deps}
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html