feat(label): use gray tokens

Author: thetaPC

core/src/components/label/label.ios.vars.scss

@@ -14,4 +14,4 @@ $label-ios-text-wrap-font-size: dynamic-font(14px);
 $label-ios-text-wrap-line-height: 1.5;
 
 /// @prop - Color of the item paragraph
-$item-ios-paragraph-text-color: $text-color-step-600;
+$item-ios-paragraph-text-color: var(--ion-color-gray-400);