🐛 Fix close button semantics

Author: AlexV525

lib/src/delegates/asset_picker_builder_delegate.dart

@@ -570,8 +570,11 @@ abstract class AssetPickerBuilderDelegate<Asset, Path> {
       padding: const EdgeInsets.symmetric(vertical: 4),
       child: IconButton(
         onPressed: Navigator.of(context).maybePop,
-        tooltip: MaterialLocalizations.of(context).backButtonTooltip,
-        icon: const Icon(Icons.close),
+        tooltip: MaterialLocalizations.of(context).closeButtonTooltip,
+        icon: Icon(
+          Icons.close,
+          semanticLabel: MaterialLocalizations.of(context).closeButtonTooltip,
+        ),
       ),
     );
   }

lib/src/delegates/asset_picker_viewer_builder_delegate.dart

@@ -702,9 +702,12 @@ class DefaultAssetPickerViewerBuilderDelegate
       leading: Semantics(
         sortKey: ordinalSortKey(0),
         child: IconButton(
-          tooltip: MaterialLocalizations.of(context).backButtonTooltip,
           onPressed: Navigator.of(context).maybePop,
-          icon: const Icon(Icons.close),
+          tooltip: MaterialLocalizations.of(context).closeButtonTooltip,
+          icon: Icon(
+            Icons.close,
+            semanticLabel: MaterialLocalizations.of(context).closeButtonTooltip,
+          ),
         ),
       ),
       centerTitle: true,