(Datepicker): apply slds-day_adjacent-month to disabled dates as well

Author: msmx-mnakagawa

src/scripts/Datepicker.tsx

@@ -246,10 +246,9 @@ const DatepickerDate: FC<DatepickerDateProps> = (props) => {
   const isToday = date.value === today;
   const isAdjacentMonth = date.month !== cal.month;
   const dateClassName = classnames({
-    'slds-color__text_gray-6': !enabled && !isAdjacentMonth,
     'slds-is-selected': selected,
     'slds-is-today': isToday,
-    'slds-day_adjacent-month': isAdjacentMonth,
+    'slds-day_adjacent-month': isAdjacentMonth || !enabled, // Considering the meaning, applying this class to disabled dates isn't necesarrily correct.
   });
   return (
     <td