message: Fix docs build on sphinx 5
diff: @@ -98,7 +98,7 @@ release = 'v{0}'.format(version)
  #
  # 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:
  