Base, holes changed.

I found that the holes were in a strange place for my skr-mini-v2 so I changed the model slightly to fit the board better. Also changed size of the fan bracket holes as they seemed a little off too.

This is a very quick, dirty change. However the mesh is good and fits my skr mini v2.

I have also provided a version that will allow a dc-dc lm2596 buck converter, also an adjusted fan bracket

Thank to the uploader for the orig file.