My crate is too large (5.7 MB above the 10 MB limit, after compression); what should I do?

I'm writing a library called rschess, and one of the features I want to provide has to do with images. For this, I need the project to have a local copy of 74 (this will probably increase in the future) PNG images, which can be opened and used by the code by their filenames.

I already have these images in the project directory, but I'm unable to publish a new version to Crates.io because my crate is too large. The size limit is 10 MB, whereas my crate is 15.7 MB after compression.

I need to be able to use these images in the code, so what alternatives do I have?