style: Type correction

Author: Jasenkoo

src/Vue3DatePicker/components/DatepickerInput.vue

@@ -19,7 +19,7 @@
         <div v-if="!$slots.trigger && !$slots['dp-input'] && !inline" class="dp__input_wrap">
             <input
                 ref="inputRef"
-                :id="uid ? `dp-input-${uid}` : null"
+                :id="uid ? `dp-input-${uid}` : undefined"
                 :class="inputClass"
                 :placeholder="placeholder"
                 :disabled="disabled"

src/Vue3DatePicker/components/DatepickerMenu.vue

@@ -1,6 +1,6 @@
 <template>
     <div
-        :id="uid ? `dp-menu-${uid}` : null"
+        :id="uid ? `dp-menu-${uid}` : undefined"
         tabindex="0"
         ref="dpMenuRef"
         role="dialog"