Veyon 4.3.1

[tobydox]

We're happy to announce Veyon 4.3.1, the first maintenance release of Veyon 4.3.x:

• Core: extend API for Addons
• LockWidget: improve compatibility with Qt 5.13 and newer (#570)
• VncView: avoid blank cursor (#550)
• VncClientProtocol: limit message size to 64 MB to prevent OOM situations
• Update 3rdparty component LibVNC to include various security fixes (although not affecting Veyon)
• Linux: fix invocation of desktop environment-specific sudo frontends (#573)
• Windows: also terminate tabtip.exe before performing logon
• Windows: improve error logging when controlling services
• Windows: update libraries (Qt 5.12.7)
• Windows: update 3rdparty component UltraVNC (various security fixes)
• Update existing translations and add Lithuanian translations