fix iconbuttons splash animation

lib/src/message_input.dart

@@ -613,8 +613,9 @@ class MessageInputState extends State<MessageInput> {
 
   Widget _buildFilePickerSection() {
     return Container(
-      color: Color(0xFFF2F2F2),
       height: _filePickerSize,
+      child: Material(
+        color: Color(0xFFF2F2F2),
         child: Column(
           children: [
             Row(
@@ -706,6 +707,7 @@ class MessageInputState extends State<MessageInput> {
             ),
           ],
         ),
+      ),
     );
   }