refactored code to work with simple popup when marker is clicked

lib/widgets/custom_marker.dart

@@ -1,15 +1,18 @@
 import 'package:flutter/material.dart';
 
 class CustomMarker extends StatelessWidget {
-  const CustomMarker({super.key, this.label});
-  final String? label;
+  const CustomMarker({super.key, required this.onTap});
+  final void Function() onTap;
 
   @override
   Widget build(BuildContext context) {
-    return Icon(
-      Icons.location_on_sharp,
-      color: Theme.of(context).colorScheme.primary,
-      size: 30,
+    return GestureDetector(
+      onTap: onTap,
+      child: Icon(
+        Icons.location_on_sharp,
+        color: Theme.of(context).colorScheme.primary,
+        size: 30,
+      ),
     );
   }
 }