Arduino Pro Micro Holder

This is a remix of the excellent design [Arduino Pro Mini Holder](https://www.thingiverse.com/thing:3562158) of [AA7JC](https://www.qrz.com/db/aa7jc) for the Arduino Pro Micro. The Pro Micro has a usb micro connector that cannot be used in the original design because the frame is in the way, though the board size is identical. The print can be done without support.