Updates for sphinx 5.0 support (#1788)

docs/source/conf.py

@@ -64,7 +64,7 @@
 copyright = "2015-%s, Jupyter Development Team" % year
 author = "Jupyter Development Team"
 
-extlinks = {"ghpull": ("https://github.com/jupyter/nbconvert/pull/%s", "PR #")}
+extlinks = {"ghpull": ("https://github.com/jupyter/nbconvert/pull/%s", "PR #%s")}
 
 linkcheck_ignore = [
     "https://github.com/jupyter/nbconvert/pull/",
@@ -88,7 +88,7 @@
 #
 # 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"
 
 # There are two options for replacing |today|: either, you set today to some
 # non-false value, then it is used: