No module named 'framepump.videolib'

Hi !

I'm getting here from trying to run **metrabs** (the pytorch version)
poseviz tries to load framepump.videolib but that doesn't exist

```
from framepump.videolib import (
    VideoFrames,
    get_duration,
    get_fps,
    get_reader,
    get_writer,
    num_frames,
    trim_video,
    video_audio_mux,
)
```