Small error in the Slicer logo (extruding edge in one corner)

There is small error in one of the corners in the Slicer logo:

![](https://user-images.githubusercontent.com/27681171/152646841-4d310492-bfa2-45bb-a00d-5f9f67062454.png)

Originally reported here:
https://github.com/Slicer/Slicer/issues/6157