python: Replace the image crate with png We weren’t using any of its features anyway, so the png crate is exactly what we need, without the many heavy dependencies of image. https://github.com/image-rs/image-png/pull/670 will eventually make it even faster to build.

cdef class LaserType:
    cdef long anim_index, launch_sprite_idx
    cdef tuple launch_anim_offsets
    cdef object anm