Flip cover for YubiKey

While Johny5's design worked, I struggled with getting the key to flip out easily. I modified the design to have a deeper cutout for pushing the key out. Also adjusted the size of the circles that hold the key in place, and made the center hole through the key larger to accommodate keyrings if desired.

Included a 3mf that will hopefully provide the right orientation, support enforcers on the clips for the key, and tighter pattern than normal for proper supports.