reverting enabled check for save button

packages/notebook/src/default-toolbar.ts

@@ -87,13 +87,7 @@ export namespace ToolbarItems {
           }
         });
       },
-      tooltip: 'Save the notebook contents and create checkpoint',
-      enabled: !!(
-        panel &&
-        panel.context &&
-        panel.context.contentsModel &&
-        panel.context.contentsModel.writable
-      )
+      tooltip: 'Save the notebook contents and create checkpoint'
     });
   }