Made diff colors a little less In Your Face

Created by: jvanbaarsen

What does this MR do? It makes the diff colors a little less bright, easier to read

Why was this MR needed? I think the old colors are to bright, makes it hard to do a lot of code reviewing. This makes the colors a bit less bright and easier on the eye.

What are the relevant issue numbers / Feature requests? None that I know of

Screenshots Before:

After: