Fixed 5 plate holder spacing

The 5 plate variant is better for my needs than the 4, and when I printed the holder and stand they did not fit together.  Since the .steps files were uploaded (thank you@ag_atlpe_362886), I looked at them and found the cause, the slots in the holder were too narrow.  I increased the width and the stand fits perfectly now.  

Slots in one side of the "holder5slots v4.step".step file were updated from 3.5mm to 5mm to match the stand post size.