Reduce image colors in Pixlet applet

I’m working on cleaning up my app on the tidbyt community repo and when I try to render the preview image like they mention (pixlet render {{MY APP NAME}} --gif --magnify 10) I get the following error:

Error rendering: require <=256 colors, found 661 in image 0

Is there a way to reduce the colors depth of the image so it fits within the limits of the command? It’s pulling the image from the internet if that’s at all helpful.