Many URLs referring to the old packages on GitHub

[jl-wynen]

Throughout the docs and in pyproject.toml, we have URLs of the old repositories pre monorepo. They all need to be updated.

Most of the URLs are generated by the general copier template. Do we still use that template? Do we need to modify the template? (@YooSunYoung )

Note that this affects the version of ESSreduce that was just released.

[YooSunYoung]

We could still use the copier template and update them...?
I was also working on the subpackage template: scipp/ess_template#13 to see if that's easier.

[jl-wynen]

I don't think simply running the template is enough because it has a certain pattern for generating URLs. We'd have to adjust that. Or move away from the general template since it includes some files that we no longer have (per repo).

[YooSunYoung]

I don't think simply running the template is enough because it has a certain pattern for generating URLs.

Yeah that's why I started a new template. The existing one will need some fixes, like the github issue page link should be ess's issue board. But that is not the case for other packages, like scippnexus or scippneutron.