fix: 🐛 Fixed showcase key issue (#578)

Author: Flamingloon

lib/src/showcase/showcase.dart

@@ -535,7 +535,7 @@ class _ShowcaseState extends State<Showcase> {
 
   late ShowcaseScope _showCaseWidgetManager;
 
-  late final int _uniqueId = widget.hashCode;
+  late final int _uniqueId = UniqueKey().hashCode;
 
   @override
   void initState() {

lib/src/showcase/showcase_controller.dart

@@ -310,7 +310,6 @@ class ShowcaseController {
               targetPadding: config.targetPadding,
             ),
             ToolTipWrapper(
-              key: ValueKey(id),
               title: config.title,
               titleTextAlign: config.titleTextAlign,
               description: config.description,

lib/src/utils/overlay_manager.dart

@@ -181,7 +181,7 @@ class OverlayManager {
       // This key is used to force rebuild the overlay when needed.
       // this key enables `_overlayEntry?.markNeedsBuild();` to detect that
       // output of the builder has changed.
-      key: ValueKey(firstShowcaseConfig.hashCode),
+      key: ValueKey(firstController.id),
       children: [
         GestureDetector(
           onTap: firstController.handleBarrierTap,
@@ -199,7 +199,7 @@ class OverlayManager {
             ),
           ),
         ),
-        ...controllers.expand((object) => object.tooltipWidgets),
+        ...controllers.expand((object) => object.tooltipWidgets).toList(),
       ],
     );