https://gitlab.xfce.org/xfce/xfdesktop/-/tags/xfdesktop-4.20.1

Should already be the case by default, but better be explicit

Now required for desktop icons support
Fixes #1

See libxfce4windowing@ccf051c6

Context: https://archlinux.org/todo/general-xfce-packages-rework/

- Update URL (point to upstream doc webpage for the package)
- Use SPDX identifier for the license
- Switch to a more transparent source (git sources)
- Add nvchecker integration (.nvchecker.toml)

- Re-enable thunarx support.
- Remove decade-old xfce4-menueditor replace.

Ref: https://mail.xfce.org/pipermail/xfce4-dev/2017-December/032085.html

Note: https://archive.xfce.org/ might still redirect to http:// mirrors
      but that should be fixed in the near future to redirect to https://

Fix FS#50729: gtk 2.24.31 regression - folders grayed out in wallpaper choose dialog