Evaluate dropping jQuery

[FestplattenSchnitzel]

jQuery isn't required (any more) in Bootstrap 5 [0] and pygal-tooltips seems to work without [1] but we seem to use it in

• sipa/static/js/register_identify.js as well as
• sipa/static/js/contact-hints.js.

[0] https://getbootstrap.com/docs/5.3/getting-started/javascript/#optionally-using-jquery [1] https://www.pygal.org/en/3.0.0/documentation/web.html

[lukasjuhrich]

Sure, that would be a good idea. In that vein, the scripts should be simplified using modern syntax (arrow functions, let/const instead of var, …)