Parametric relay case

This is an updated version of [thing:3188687](https://www.thingiverse.com/thing:3188687) that reduces the size of the control-pin hole to something more reasonable.

The default values have been updated to match my Onyehn relays (https://www.amazon.com/gp/product/B07PNB86R7). These are 3.3V relays (both power and logic), and are compatible with a Raspberry Pi GPIO's 3.3V logic level.