iOS 26 compatibility, Larger Text support

• Compatibility with iOS 26
• Support for Larger Text (Settings page to be finalised in next release)
• JPEG XL format support (requires iOS 18.2)
• Stops animating a refresh after a force refresh when the app is already being fetching data
• Replaces deprecated code
• Prepares the migration to Swift 6

Full Changelog: v3.5.1...v4.0