update to flutter version 3

lib/bottom_sheet/multi_select_bottom_sheet.dart

@@ -128,7 +128,6 @@ class _MultiSelectBottomSheetState<V> extends State<MultiSelectBottomSheet<V>> {
     return Theme(
       data: ThemeData(
         unselectedWidgetColor: widget.unselectedColor ?? Colors.black54,
-        accentColor: widget.selectedColor ?? Theme.of(context).primaryColor,
       ),
       child: CheckboxListTile(
         checkColor: widget.checkColor,

lib/dialog/mult_select_dialog.dart

@@ -122,7 +122,6 @@ class _MultiSelectDialogState<V> extends State<MultiSelectDialog<V>> {
     return Theme(
       data: ThemeData(
         unselectedWidgetColor: widget.unselectedColor ?? Colors.black54,
-        accentColor: widget.selectedColor ?? Theme.of(context).primaryColor,
       ),
       child: CheckboxListTile(
         checkColor: widget.checkColor,

pubspec.yaml

@@ -7,7 +7,7 @@ documentation: https://github.com/CHB61/flutter-multi-select
 homepage: https://github.com/CHB61/flutter-multi-select
 
 environment:
-  sdk: '>=2.12.0 <3.0.0'
+  sdk: '>=3.2.0 <4.0.0'
 
 dependencies:
   flutter: