Label: Prevent overwriting disabled_color attribute when color …

…is updated (#8667)

Ensure that when setting rules for color and disabled_color, refrain from overwriting color attributes if the label is disabled, allowing the label to be drawn using the disabled_color value.

kivy/uix/label.py

@@ -379,6 +379,10 @@ def _trigger_texture_update(self, name=None, source=None, value=None):
                 self._label.options['outline_color'] = (
                     self.disabled_outline_color if value else
                     self.outline_color)
+            elif self.disabled and name in ('color', 'outline_color'):
+                # When disabled, color or outline_color changes should not get
+                # assigned or trigger updates.
+                return
 
             # NOTE: Compatibility code due to deprecated properties
             # Must be removed along with padding_x and padding_y