v8.4.15: HEIC/HEIF support, better non-Latin text rendering v8.4.15

Ultralytics v8.4.15 shipped with proper HEIC/HEIF image support. We added lazy decoding via pi-heif so you're not dragging in dependencies you don't need, plus better EXIF handling and expanded .heif extension support. Also fixed plotting for non-Latin text because Arial Unicode MS should've been the default ages ago. Patch release, but genuinely useful if you're working with real-world images from iPhones and modern cameras.