Switch to newer openstackdocstheme version

Switch to openstackdocstheme 2.2.1 version. Using
this version will allow especially:
* Linking from HTML to PDF document
* Allow parallel building of documents
* Fix some rendering problems

Update Sphinx version as well.

Change pygments_style to 'native' since old theme version always used
'native' and the theme now respects the setting and using 'sphinx' can
lead to some strange rendering.

openstackdocstheme renames some variables, so follow the renames
before the next release removes them. A couple of variables are also
not needed anymore, remove them.

See also
http://lists.openstack.org/pipermail/openstack-discuss/2020-May/014971.html

Change-Id: I778b288f3b478c0fe1718bf5517c2c818b8d305e

doc/source/conf.py

@@ -43,7 +43,7 @@ project = u'reno'
 copyright = u'2013, OpenStack Foundation'
 
 # The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
+pygments_style = 'native'
 
 # Do not warn about non-local image URI
 suppress_warnings = ['image.nonlocal_uri']
@@ -54,6 +54,5 @@ suppress_warnings = ['image.nonlocal_uri']
 if has_theme:
     html_theme = 'openstackdocs'
 
-repository_name = 'openstack/reno'
-bug_project = '933'
-bug_tag = 'docs'
+openstackdocs_repo_name = 'openstack/reno'
+openstackdocs_use_storyboard = True

lower-constraints.txt

@@ -1,5 +1,5 @@
 docutils==0.11
 dulwich==0.15.0
 PyYAML==3.10.0
-Sphinx==1.6.1
+Sphinx==2.0.0
 stestr==2.1.0

setup.cfg

@@ -32,7 +32,7 @@ distutils.commands =
 
 [extras]
 sphinx =
-  sphinx>=1.6.1,!=1.6.6,!=1.6.7,!=2.1.0  # BSD
+  sphinx>=2.0.0,!=2.1.0  # BSD
   docutils>=0.11  # OSI-Approved Open Source, Public Domain
 
 [compile_catalog]

test-requirements.txt

@@ -5,7 +5,7 @@
 
 coverage!=4.4,>=4.0 # Apache-2.0
 python-subunit>=0.0.18
-openstackdocstheme>=1.11.0 # Apache-2.0
+openstackdocstheme>=2.2.1 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0
 testscenarios>=0.4
 testtools>=1.4.0