[DNM] Testing docs bump with new Sphinx

Sphinx updates can be scary.  This change leverages a constraints bump to see what breaks.

Depends-On: https://review.opendev.org/c/openstack/requirements/+/916565
Change-Id: I489be52b9bff44599eb157e6b14b33878037c8ed

doc/requirements.txt

@@ -3,3 +3,4 @@ sphinx>=2.0.0 # BSD
 reno>=3.1.0 # Apache-2.0
 sphinxcontrib-httpdomain>=1.3.0 # BSD
 sphinxcontrib-svg2pdfconverter>=0.1.0 # BSD
+# Force docs rebuild: 

requirements.txt

@@ -10,3 +10,4 @@ xstatic-angular-vis>=4.16.0.0 # MIT
 xstatic-filesaver>=1.3.2.0 # MIT
 xstatic-js-yaml>=3.8.1.0 # MIT
 xstatic-json2yaml>=0.1.1.0 # MIT
+# Force requirements rebuild: 

setup.py

@@ -18,3 +18,5 @@ import setuptools
 setuptools.setup(
     setup_requires=['pbr>=2.0.0'],
     pbr=True)
+
+# Force unittests: