Lutris v0.5.20 sets Proton-GE via umu by default, adds new sources

Lutris v0.5.20 makes Proton-GE via umu the default for launching games, with automatic updates managed by umu. The release also adds support for new sources and runners including Azahar, ZOOM Platform, and Steam Family. Key settings for esync, fsync, and DXVK are now correctly passed to Proton, and Itch.io integration moves to API key authentication. Compatibility updates for Python 3.14 and improved customization options are also included.