Specify adafruit_imageload dependencies

[wormyrocks]

This project inherits the adafruit_imageload dependency from the bongo repo, but doesn't mention it in README. I'm not sure what best practices are for Adafruit package managed stuff, but it might be good either to include adafruit_imageload in /lib, or at least to link back to the installation instructions for circuitpython-bongo that resolve the dependency.

Cheers, I hope to contribute to this soon. Pomodoro timers are useful.

[notnavindu]

Thanks for catching that @wormyrocks. I added the adafruit_imageload library to /lib 🍻