Converts an ImageBuffer to a 128x64 SSD1306 OLED byte vector
rust
let image_buffer: ImageBuffer<Rgb<u8>, Vec<u8>> =
ImageBuffer::from_vec(2, 2, vec![30; 12]).unwrap();
// get bytes vec, specifying the brightness threshold
// as a number between 0 and 255
let bytes = to_oled_bytes(&image_buffer, 30);