Log Message:
xfce4-conf: update to 4.18.1

Change log:

4.18.1 (2023-04-17)
======
- Update copyright year
- xfconfd: Lower warning level
- docs: Fix xfconf_channel_get() transfer annotation
- Update bug report address
- docs: Fix unused declarations warning
- docs: Properly enable GI docs
- xfconfd: Fix check for "/" when building property name
- xfconfd: Make xml backend case sensitive for channel names
- Translation Updates:
  Albanian, Armenian (Armenia), Basque, Belarusian, Bulgarian, Catalan,
  Chinese (China), Chinese (Hong Kong), Chinese (Taiwan), Croatian,
  Czech, Danish, Dutch, Eastern Armenian, English (Australia), English
  (Canada), English (United Kingdom), Finnish, French, Galician,
  German, Greek, Hebrew, Hindi, Hungarian, Icelandic, Indonesian,
  Italian, Japanese, Kazakh, Korean, Lithuanian, Malay, Norwegian
  Bokml, Occitan (post 1500), Polish, Portuguese, Portuguese
  (Brazil), Romanian, Russian, Serbian, Slovak, Slovenian, Spanish,
  Swedish, Thai, Turkish, Ukrainian