fix(date-picker): adjust style slectors for disabled or prev/next days (carbon-design-system#5085)

Author: abbeyhrt

packages/components/src/components/date-picker/_date-picker.scss

@@ -316,9 +316,9 @@
     }
   }
 
-  .#{$prefix}--date-picker__days .nextMonthDay,
-  .#{$prefix}--date-picker__days .prevMonthDay {
-    color: $text-02;
+  .#{$prefix}--date-picker__day.nextMonthDay,
+  .#{$prefix}--date-picker__day.prevMonthDay {
+    color: $text-05;
   }
 
   .#{$prefix}--date-picker__day.today,
@@ -352,11 +352,10 @@
     }
   }
 
-  .#{$prefix}--date-picker__day.disabled,
-  .flatpickr-day.disabled {
+  .#{$prefix}--date-picker__day.flatpickr-day.flatpickr-disabled {
     cursor: not-allowed;
     opacity: 0.5;
-    color: $ui-05;
+    color: $disabled-02;
 
     &:hover {
       background: transparent;