Psi+ Linux appimage still at 1.5.1515

[henry3343]

Please update appimage, security and certificate bugs in current version.

[Neustradamus]

Linked to:

• [OS] [Linux] AppImage update is needed psi-im/psi#933
• [OS] [Linux] [Debian] New version before Debian 13 "Trixie" release? psi-im/psi#860
• [OS] [macOS] An update is needed psi-im/psi#832
• [OS] [Linux] [Debian] [Ubuntu] An update is needed psi-im/psi#831
• Debian: Psi is not really here like other XMPP clients psi-im/psi#612
• Psi+ Linux appimage still at 1.5.1515 #800
• More frequent (macOS) releases/builds? maintenance#22