Implement Flathub.org verification

[loganmarchione]

Not sure if this belongs in this repo or the packaging repo...

The official KeePassXC download page has instructions to install via Flatpak. Who maintains this Flatpak on Flathub (repo here)? I'm assuming that since Flatpak is mentioned on keepassxc.org that it's officially maintained by KeePassXC. Per this, the Flatpak is official, right?

If that is the case, you should look into verifying your application on Flathub. Flathub's Beta site is rolling out blue-checkmark verification so that the community knows that the Flatpak app is official from the developer.

The Flathub Beta site has an entire section of verified applications. For example, look at the blue checkmarks on LibreOffice, Firefox, and OBS.

There is a post here about how to get verified.

Being verified would let users know that one of their most important apps (a password manager) is directly from the developer, not a third-party. Plus, you could add the word "Official" to the Flatpak on the Download page, like AppImage and Snap have.

[droidmonkey]

Done!