v1.3.0

• added option to return UpdateEvent::Capture from the update() function to capture in-game screenshots
• added max_fps to AppOptions to lower the frame rate even below the screen vsync frequency. See lowfps example.
• switched to unrust 0.2 to run on the latest winit/glutin/wasm_bindgen/web-sys versions
• upgraded to image 0.23.14 to fix a vulnerability