Use LightGrey for the skip colour

This isn't great, but is better than the deep blue that was borderline
invisible on dark backgrounds. The fix is to redo the colouring
a bit, including introducing light-blue that is actually visible.

src/catch2/internal/catch_console_colour.hpp

@@ -47,7 +47,7 @@ namespace Catch {
 
             Error = BrightRed,
             Success = Green,
-            Skip = Blue,
+            Skip = LightGrey,
 
             OriginalExpression = Cyan,
             ReconstructedExpression = BrightYellow,