Upgrade jQuery to 3.5.x for Notebook 5.x

[dylanraws]

As reported in #5489, jQuery versions below 3.5.0 have known security vulnerabilities. My organization provides customers with a managed compute environment with Jupyter Notebook 5.x installed. Our customers have the requirement that we update jQuery to resolve known CVEs. Long term, we will work with our customers to use newer major versions of Jupyter Notebook and Jupyter Lab, but for now, we ask that the jQuery version be upgraded and a new version of Jupyter Notebook 5.x be released.

[dylanraws]

Tagging @jweill-aws for visibility

[jtpio]

Closing as this would have to be implemented in https://github.com/jupyter/nbclassic if still needed.

Please open a new issue there if the issue is still relevant, thanks!