squelch warnings (#9689)

pytest.ini

@@ -23,10 +23,13 @@
 #    See https://github.com/certbot/certbot/issues/6284.
 # 5) Ignore pkg_resources.declare_namespace used in a large number of Google's Python
 #    libs. e.g. https://github.com/googleapis/google-auth-library-python/issues/1229.
+#    It is also is used in sphinxcontrib-devhelp 1.0.2 which as of writing this
+#    is the latest version of that library. See
+#    https://github.com/sphinx-doc/sphinxcontrib-devhelp/blob/1.0.2/setup.py#L69.
 filterwarnings =
     error
     ignore:decodestring\(\) is a deprecated alias:DeprecationWarning:dns
     ignore:.*rsyncdir:DeprecationWarning
     ignore:'urllib3.contrib.pyopenssl:DeprecationWarning:requests_toolbelt
     ignore:update_symlinks is deprecated:PendingDeprecationWarning
-    ignore:.*declare_namespace\('google:DeprecationWarning
+    ignore:.*declare_namespace\(':DeprecationWarning