some widgets (feedback) use JQuery, if you want to control the version which is loaded use the index.html
For a custom widget I needed the UI extension as well for dragging and dropping. What I did was download the latest jQuery UI version at:
https://jqueryui.com/download/all/
I added this file to a separate folder in my widget (/root/lib) and in the main javascript file of my widget I added the line dojo.require("root.lib.jquery-ui-min");
This worked for me.