[flatpak] Gtk-warnings

- _v._: 2.2.0, as communicated by flathub.org; the version not even being communicated by the application itself.
- _OS_: Fedora v. 43
- _DE_: Gnome v. 49, Wayland session

Hello. Deluge of warnings related to Gtk.
```
$ flatpak run io.github.ellie_commons.reminduck

💲️ Command line mode started
✔️ Interface
✔️ Activated
Environment: GNOME detected!MESA-INTEL: warning: ../src/intel/vulkan/anv_formats.c:949: FINISHME: support YUV colorspace with DRM format modifiers
MESA-INTEL: warning: ../src/intel/vulkan/anv_formats.c:981: FINISHME: support more multi-planar formats with DRM modifiers

(io.github.ellie_commons.reminduck:2): Gtk-WARNING **: 13:53:33.541: Trying to measure ReminduckMainWindow 0x55c7fe920040 for height of 457, but it needs at least 677

(io.github.ellie_commons.reminduck:2): Gtk-WARNING **: 13:53:33.566: Trying to measure GranitePlaceholder 0x55c7fe8eb1a0 for height of 251, but it needs at least 471

[...]
```