Remove insecure X11 permission

You currently use the X11 permission. I manually removed it locally for me with Flatseal, and it seems not to be needed and is also insecure.

> Applications that do not support native Wayland should use only --socket=x11 and applications that do, should use --socket=fallback-x11 and --socket=wayland. The two configurations here will make the application work on both X11 and Wayland sessions of the desktop environment.

https://docs.flatpak.org/en/latest/sandbox-permissions.html

Alternatively, you could at least use `fallback-x11`?

I saw https://github.com/flathub/com.github.mtkennerly.ludusavi/issues/24 but really, as said, it works fine for me (on Wayland/Bazzite 44) and I do not see whether that permission was the same before anyway.

Start with the Flatpak sandbox permissions documentation linked in the issue, then inspect the application's Flatpak permission configuration. Done means the unnecessary X11 permission is removed or replaced with the appropriate fallback configuration while retaining operation on the supported desktop sessions.

Written by the indexing model from the issue text.