Wrong svg to png conversion after latest update

In the latest updates when an SVG is converted to png the output does not come as expected (the colors are lost). I believe its because of the change in the cairosvg/image.py file where a check is added to convert "CMYK" to "RGB".

```
82 if image.mode == "CMYK":
83 image = image.convert("RGB")
```

Can I ask what is this doing. Maybe there is a problem while converting CMYK to RGB.
Sorry I am not providing the files but I found the error after updating and then rolled back to the previous version.

Start in cairosvg/image.py at the CMYK-to-RGB conversion around lines 82-83 and compare the behavior with the previous version. Obtain a reproducible SVG or expected PNG output, then verify that the conversion preserves the intended colors before adding a regression test.

Written by the indexing model from the issue text.