chore: don't ask location permission in demo app for web platform

Author: ilfa

example/lib/main.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:convert';
 
 import 'package:env_flutter/env_flutter.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:fpjs_pro_plugin/error.dart';
 import 'package:fpjs_pro_plugin/fpjs_pro_plugin.dart';
@@ -82,6 +83,9 @@ class _MyAppState extends State<MyApp> {
   }
 
   Future<void> requestLocationPermission() async {
+    if (kIsWeb) {
+      return;
+    }
     LocationPermission permission = await Geolocator.checkPermission();
     if (permission == LocationPermission.denied) {
       permission = await Geolocator.requestPermission();