Bump the openstackdocstheme extension to 1.20

Some options are now automatically configured by the version 1.20:
- project
- html_last_updated_fmt
- latex_engine
- latex_elements
- version
- release.

Change-Id: Ic626d2dc2974ac6ac7b6a816963995915e723ec7

doc/requirements.txt

@@ -5,4 +5,4 @@
 sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7'  # BSD
 sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4'  # BSD
 reno>=2.5.0
-openstackdocstheme>=1.18.1
+openstackdocstheme>=1.20.0

doc/source/conf.py

@@ -15,7 +15,6 @@ sys.path.insert(0, os.path.abspath('../..'))
 # -- Project information -----------------------------------------------------
 
 # General information about the project.
-project = 'oslo.upgradecheck'
 copyright = '2018, Oslo Contributors'
 
 

lower-constraints.txt

@@ -7,4 +7,4 @@ oslotest==1.5.1
 stestr==2.0.0
 sphinx==1.6.2
 reno==2.5.0
-openstackdocstheme==1.18.1
+openstackdocstheme==1.20.0

releasenotes/source/conf.py

@@ -8,7 +8,6 @@
 
 # -- Project information -----------------------------------------------------
 
-project = 'oslo.upgradecheck'
 copyright = '2018, Oslo Contributors'
 author = 'Oslo Contributors'