fix(date_utils): update getDayOfWeekCode to use "E" format instead of "ddd"

Author: FLT4613

src/date_utils.ts

@@ -325,7 +325,7 @@ export function getWeek(date: Date): number {
  * @returns - The day of the week code.
  */
 export function getDayOfWeekCode(day: Date, locale?: Locale): string {
-  return formatDate(day, "ddd", locale);
+  return formatDate(day, "E", locale);
 }
 
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