Use kibot to generate diffs

[CloudyPadmal]

Instead of terminal based diff images, now kibot has an option called 'diff' that generate diff pdfs between schematics and PCBs. (https://github.com/INTI-CMNB/KiBot)

We may use that for reviewing changes.

[CloudyPadmal]

Fixes in #146

[bessman]

Cool!

How does one read the diffs? At a glance, the diff_schematic.pdf looks identical to PSLab.pdf, just in black-and-white.

[CloudyPadmal]

Something is not right with the diff configuration in CI.kibot.yaml. The PDF should look like this: diff_schematic.pdf with red and green stuff

[CloudyPadmal]

Now it works! 🚀