Update to FreeDesktop Runtime 25.08

[NoTuxNoBux]

Mostly just a blind update without testing to get the ball rolling for #147 and see what the fallout is.

[flathubbot]

🚧 Test build enqueued.

[flathubbot]

🚧 Started test build.

[flathubbot]

✅ Test build succeeded. To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/212172/com.unity.UnityHub.flatpakref

[NoTuxNoBux]

Initial test seems positive, will give it a few days of testing before pushing definitively.

[NoTuxNoBux]

Okay at first I could open the editor but now I suddenly can't any more:

./Unity: error while loading shared libraries: libxml2.so.2: cannot open shared object file: No such file or directory

[flathubbot]

🚧 Test build enqueued.

[flathubbot]

🚧 Started test build.

[flathubbot]

✅ Test build succeeded. To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/252171/com.unity.UnityHub.flatpakref

Built for x86_64 architecture.