feat: Update backbone.js to new version

Author: vipul0425

package.json

@@ -143,7 +143,7 @@
 		"@wordpress/warning": "3.19.1",
 		"@wordpress/widgets": "4.19.6",
 		"@wordpress/wordcount": "4.19.1",
-		"backbone": "1.6.0",
+		"backbone": "1.6.1",
 		"clipboard": "2.0.11",
 		"core-js-url-browser": "3.6.4",
 		"element-closest": "3.0.2",