Printhead fix for marcoa131's Poison Sherpa Mini V6 Clone remix

To this date ( 23. Feb 2023 ), the print head model remixed by Marcoa131 does have different screw hole diameters between the front and rear attachment side. 

This issue does also exist in the originate model created by robbin. 

My changes to the design is: 

Front and rear m4 screwhole diameter set to 3.8mm 

4010 fan attachment posts slightly angled to make broader compatibility to other fan manufacturers. 

My thanks go to robbin for creating this remarkable design, and to marcoa131 for the nice v6 and sherpa mod.