add curve property to bottomsheet

@@ -21,6 +21,7 @@ class GetModalBottomSheetRoute<T> extends PopupRoute<T> {
     RouteSettings? settings,
     this.enterBottomSheetDuration = const Duration(milliseconds: 250),
     this.exitBottomSheetDuration = const Duration(milliseconds: 200),
+    this.curve,
   }) : super(settings: settings) {
     RouterReportManager.instance.reportCurrentRoute(this);
   }
@@ -38,6 +39,7 @@ class GetModalBottomSheetRoute<T> extends PopupRoute<T> {
   // final String name;
   final Duration enterBottomSheetDuration;
   final Duration exitBottomSheetDuration;
+  final Curve? curve;
   // remove safearea from top
   final bool removeTop;
 
@@ -62,6 +64,15 @@ class GetModalBottomSheetRoute<T> extends PopupRoute<T> {
   }
 
   @override
+  Animation<double> createAnimation() {
+    if (curve != null) {
+      return CurvedAnimation(
+          curve: curve!, parent: _animationController!.view);
+    }
+    return _animationController!.view;
+  }
+  
+  @override
   AnimationController createAnimationController() {
     assert(_animationController == null);
     _animationController =