AVIF/WebP support using the Vary Accept HTTP header?

This project looks interesting. Thanks for sharing it. Does it support checking the `Vary` `Accept` HTTP header and therefore have compatibility with the improxy params:

- `IMGPROXY_AUTO_WEBP` and `IMGPROXY_ENFORCE_WEBP`
- `IMGPROXY_AUTO_AVIF` and `IMGPROXY_ENFORCE_AVIF`

The readme suggests that it doesn't, but I wanted to check.

Thanks.