kea: fix build with Sphinx 5.0

srcpkgs/kea/patches/sphinx-5.0.patch

@@ -0,0 +1,11 @@
+--- a/doc/sphinx/conf.py
++++ b/doc/sphinx/conf.py
+@@ -67,7 +67,7 @@ messages_doc = 'kea-messages'
+ #
+ # This is also used if you do content translation via gettext catalogs.
+ # Usually you set "language" from the command line for these cases.
+-language = None
++language = 'en'
+ 
+ # List of patterns, relative to source directory, that match files and
+ # directories to ignore when looking for source files.