Revert "primefaces#16686 fix: incorrect month value in Calendar compo…

…nent"

This reverts commit 3192fbe.

src/app/components/calendar/calendar.ts

@@ -1643,7 +1643,7 @@ export class Calendar implements OnInit, OnDestroy, ControlValueAccessor {
     }
 
     formatDateKey(date: Date): string {
-        return `${date.getFullYear()}-${date.getMonth() + 1}-${date.getDate()}`;
+        return `${date.getFullYear()}-${date.getMonth()}-${date.getDate()}`;
     }
 
     setCurrentHourPM(hours: number) {