Revolt v1.0.4

Small quality of life improvements and minor bug fixes:

• feat: prevent launching multiple instances (https://github.com/revoltchat/desktop/issues/82)
• feat: add a tray icon (https://github.com/revoltchat/desktop/issues/2)
• feat: allow minimising the app to the tray
• feat: allow zooming in with "CTRL + =" (https://github.com/revoltchat/desktop/issues/8)
• fix: artifact like shapes on start (https://github.com/revoltchat/desktop/pull/57)
• feat: add spell check
• fix: bundle window icon correctly
• feat(ci): generate DMG rather than ZIP