fix: Remove -1 from maxMonth

Author: Jasenkoo

src/Vue3DatePicker/components/MonthYearInput.vue

@@ -238,7 +238,7 @@
     const maxMonth = computed(() => {
         if (props.maxDate && maxYear.value) {
             if (maxYear.value < props.year) return -1;
-            if (maxYear.value === props.year) return getMonth(new Date(props.maxDate)) - 1;
+            if (maxYear.value === props.year) return getMonth(new Date(props.maxDate));
         }
         return null;
     });