Fix priority icon colors

Priority icons 2 and 3 used colors from icon 1.

Author: Riksu9000

core/Util/Util.vala

@@ -912,12 +912,12 @@ public class Util : GLib.Object {
             };
         } else if (priority == Constants.PRIORITY_2) {
             return new Gtk.Image.from_icon_name ("flag-outline-thick-symbolic") {
-                css_classes = { "priority-1-icon" },
+                css_classes = { "priority-2-icon" },
                 pixel_size = 16
             };
         } else if (priority == Constants.PRIORITY_3) {
             return new Gtk.Image.from_icon_name ("flag-outline-thick-symbolic") {
-                css_classes = { "priority-1-icon" },
+                css_classes = { "priority-3-icon" },
                 pixel_size = 16
             };
         } else if (priority == Constants.PRIORITY_4) {