core: graphics: use pressed color for pressed keys

The locked label color is a special color that displays when the user
holds a modifier key for very long. In !7, this locked color replaced
the color for the pressed non-modifier key with no explanation. Revert
the change and use the "label_pressed" color for a non-modifier key
being pressed.

src/core/graphics.rs

@@ -510,7 +510,7 @@ impl<D: Display> Graphics<D> {
         }
 
         if part.presses() != 0 {
-            return colors.label_locked;
+            return colors.label_pressed;
         }
 
         if sublabel {