Flathub screenshot - show the Linux version instead of macOS one.

[latenightdef]

Currently Jitsi Meet on Flathub displays a screenshot from the Mac app. I think it would be better to use a screenshot from an actual Linux system so people can know how it will look like when installed on a Linux system.

[ananace]

The screenshot is taken directly from upstream, as I wanted to follow their wishes to keep the Flatpak as close to their AppImage as possible.
It's definitely in need of a refresh at this point though, perhaps an issue towards upstream to have fresh screenshots taken for their supported platforms - Linux, Mac, Windows - would be a good idea.

[csett86]

Upstream here :)

Thanks for the hint, adding a linux screenshot for how here: jitsi/jitsi-meet-electron#972