added reason for using User Defaults API to iOS privacy manifest (#2294)

Co-authored-by: ryouta-miyauchi <[email protected]>

flutter_local_notifications/ios/Resources/PrivacyInfo.xcprivacy

@@ -5,7 +5,16 @@
 	<key>NSPrivacyTrackingDomains</key>
 	<array/>
 	<key>NSPrivacyAccessedAPITypes</key>
-	<array/>
+	<array>
+		<dict>
+			<key>NSPrivacyAccessedAPIType</key>
+			<string>NSPrivacyAccessedAPICategoryUserDefaults</string>
+			<key>NSPrivacyAccessedAPITypeReasons</key>
+			<array>
+				<string>CA92.1</string>
+			</array>
+		</dict>
+	</array>
 	<key>NSPrivacyCollectedDataTypes</key>
 	<array/>
 	<key>NSPrivacyTracking</key>