Update sphinx_rtd_theme (Azure#22197)

Author: danieljurek

eng/tox/tox.ini

@@ -1,7 +1,7 @@
 
 # This tox file is intended for use with any generic development feed. The only requirement is that the development feed
 # contain azure* prefixed packages. It does this by assuming that `PIP_INDEX_URL` environment variable is set to target the dev feed
-# specifically. Notice that in the [testenv] config, we explicitly set PIP_EXTRA_INDEX_URL to pypi. 
+# specifically. Notice that in the [testenv] config, we explicitly set PIP_EXTRA_INDEX_URL to pypi.
 
 # In all cases, whenever we install an azure-* package from a requirement (read: not a specific file), the only source will be from the dev feed.
 # once we've downloaded these dependencies, only then do we install other packages from pypi. 
@@ -150,7 +150,7 @@ passenv = *
 deps =
   {[base]deps}
   sphinx==3.5.4
-  sphinx_rtd_theme==0.5.0
+  sphinx_rtd_theme==1.0.0
   recommonmark==0.6.0
   mistune<2.0.0
   m2r==0.2.1