Update jQuery 3.5.1 to 3.7.1

[wenz]

Some of the templates are using a bundled version of jQuery 3.5.1. This was last updated in May 2020 shortly after jQuery 3.5.1 itself was released.

While there are no active CVEs in that version, it is now ~4.5 years old and might trigger warnings in static code/dependency analysis tools. The current latest version of jQuery 3.x is 3.7.1, released in August 2023.

I am aware that eventually jQuery will be replaced once HTML-only validators are used, but until then, it makes sense to use an up-to-date version in the templates so that developers do not have to upgrade dependencies once they start working