fix(notification): follow notification palette theme

Author: JinParc

packages/ra-ui-materialui/src/layout/Notification.tsx

@@ -139,12 +139,12 @@ const StyledSnackbar = styled(Snackbar, {
     },
 
     [`& .${NotificationClasses.error}`]: {
-        backgroundColor: theme.palette.error.dark,
+        backgroundColor: theme.palette.error.main,
         color: theme.palette.error.contrastText,
     },
 
     [`& .${NotificationClasses.warning}`]: {
-        backgroundColor: theme.palette.error.light,
+        backgroundColor: theme.palette.warning.main,
         color: theme.palette.error.contrastText,
     },