Switch to newer openstackdocstheme and reno versions

Switch to openstackdocstheme 2.2.1 and reno 3.1.0 versions. Using
these versions will allow especially:
* Linking from HTML to PDF document
* Allow parallel building of documents
* Fix some rendering problems

Update Sphinx version as well.

Disable openstackdocs_auto_name to use 'project' variable as name.

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.

Remove docs requirements from lower-constraints, they are not needed
during install or test but only for docs building.

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: Iee357adb23ff65e453ac627eaec0b9d7ac245ba6

1 files changed, 5 insertions, 5 deletions

diff --git a/releasenotes/source/conf.py b/releasenotes/source/conf.py
index b91665c..b64031d 100644
--- a/releasenotes/source/conf.py
+++ b/releasenotes/source/conf.py
@@ -38,10 +38,10 @@ extensions = [
 ]
 
 # openstackdocstheme options
-repository_name = 'openstack/glance_store'
-bug_project = 'glance-store'
-bug_tag = ''
-html_last_updated_fmt = '%Y-%m-%d %H:%M'
+openstackdocs_repo_name = 'openstack/glance_store'
+openstackdocs_auto_name = False
+openstackdocs_bug_project = 'glance-store'
+openstackdocs_bug_tag = ''
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
@@ -93,7 +93,7 @@ exclude_patterns = []
 # show_authors = False
 
 # The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
+pygments_style = 'native'
 
 # A list of ignored prefixes for module index sorting.
 # modindex_common_prefix = []