Large dependency tree

I'm using this crate on a Raspberry Pi as part of my Sense HAT driver. Unfortunately it takes about 5 minutes to build (on the fastest Pi 3B+), and that seems a lot for just reading and writing some bytes from /dev/i2c. From the tree it looks like `skeptic` is pulling in most of it - is this crate strictly required, and/or is there any chance it could be placed behind a feature flag? Thanks!