xfce4-panel: update to 4.18.3

Change log:

4.18.3 (2023-03-28)
======
- launcher: Show action menu also when there are several items
- Fix memory management of vala generated plugins
- panel: Rephrase "Don't reserve space on borders" (V2)
- panel: Make property migration generic
- launcher: Avoid "no trigger event" warning when showing the menu
- launcher: Guard access to the plugin menu GdkWindow
- libxfce4panel: Unregister menu also on GtkWidget::hide
- panel: Do not reset output name if a monitor does not have a model
name
- libxfce4panel: Fix memory management of source for menu positioning
- panel: Delay removal of ExternalPlugin to prevent use-after-free
- systray: Cancel any async D-Bus operation in finalize()
- tasklist: Do not try to resolve /proc/pid/exe to launch new instance
- Translation Updates:
  Albanian, Arabic, Armenian (Armenia), Asturian, Basque, Belarusian,
  Bulgarian, Catalan, Chinese (China), Chinese (Hong Kong), Chinese
  (Taiwan), Croatian, Czech, Danish, Dutch, Eastern Armenian, English
  (Australia), English (United Kingdom), Estonian, Finnish, French,
  Galician, German, Greek, Hebrew, Hungarian, Icelandic, Indonesian,
  Italian, Japanese, Kazakh, Korean, Lithuanian, Malay, Norwegian
  Bokm奪l, Norwegian Nynorsk, Occitan (post 1500), Polish, Portuguese,
  Portuguese (Brazil), Romanian, Russian, Serbian, Slovak, Slovenian,
  Spanish, Swedish, Thai, Turkish, Ukrainian, Uyghur, Vietnamese

4.18.2 (2023-02-09)
======
- directorymenu: Add missing sanity check
- panel: Properly handle null string as property default value
- Revert "Use RGBA visual only if compositing is enabled (Fixes #251)" (#672)
- Revert "systray: Do not require compositing to be enabled to use RGBA visual"
- systray: Fix blurry icons in prefs dialog when UI scale > 1
- launcher: Fix blurry icons in prefs and add dialogs when UI scale > 1
- launcher: Use GIcon for the tooltip icon (#674)
- pager: Use WnckHandle if available (#695)
- Translation Updates:
  Albanian, Finnish, Greek, Italian, Portuguese, Slovenian

4.18.1 (2023-01-10)
======
- Update copyright year
- tasklist: Fix scrolling through window buttons (Fixes #692)
- tasklist: Fix group button visibility
- libxfce4panel: Deprecate XfcePanelImage
- tasklist: Do not duplicate menu item activation
- clock: Fix sync timeout
- docs: Fix version for xfce_panel_set_image_from_source()
- clock: Add missing sanity check
- windowmenu: Adapt wnck default icon size when UI scale > 1 (Fixes
#682)
- tasklist: Adapt wnck default icon size when UI scale > 1 (Fixes #681)
- tasklist: Fix window count positioning when UI scale > 1
- tasklist: Keep icon pixbuf around and use surface also for menu items
- clock: Do not override custom font formats
- Translation Updates:
  Albanian, Amharic, Arabic, Armenian (Armenia), Asturian, Basque,
  Belarusian, Bengali, Bulgarian, Catalan, Chinese (China), Chinese
  (Hong Kong), Chinese (Taiwan), Croatian, Czech, Danish, Dutch,
  Eastern Armenian, English (Australia), English (United Kingdom),
  Estonian, Finnish, French, Galician, Georgian, German, Greek, Hebrew,
  Hungarian, Icelandic, Indonesian, Interlingue, Italian, Japanese,
  Kazakh, Korean, Lithuanian, Malay, Norwegian Bokm奪l, Norwegian
  Nynorsk, Occitan (post 1500), Panjabi (Punjabi), Polish, Portuguese,
  Portuguese (Brazil), Romanian, Russian, Serbian, Sinhala, Slovak,
  Slovenian, Spanish, Swedish, Thai, Turkish, Ukrainian, Uyghur,
  Vietnamese

(gutteridge)