Don't update the copyright year

[seanh]

Don't update the copyright year in the LICENSE file to the current year. Otherwise every year the cookiecutter is going to want to update the LICENSE file in every project.

If we actually want to automate updating copyright years one day we can do that: just write a script the reads cookiecutter.json, changes __copyright_year, writes it back, and runs make template. Commando or another tool could be used to run such a script on every project and send PRs. But I don't think we need to update these.

Anyway, this PR just prevents make template from making this change by itself, which I think is clearly undesirable

[seanh]

It defaults to the current year when generating a new project. Thereafter it'll use the __copyright_year in the project's cookiecutter.json file.

The __ is so that cookiecutter doesn't interactively ask the user for the copyright year when creating a new project. It has to be __ not just _ to enable Jinja2 in the value. If you wanted to specify a different copyright year for a new project for some reason you could pass it as a command line argument: cookiecutter gh:hypothesis/cookiecutters ... __copyright_year=1981

[jon-betts]

I think this is the correct behavior. As I understand it we don't / shouldn't want to update the copyright date ever really.

This is because the date provides the starting point of copyright protection (+50 / 70 years). If you "update" the value, you strip yourself of historical protection. This means should someone else have copied the work in the mean time, and has a prior date to us, it will appear as if we stole the work rather than the other way around.

I believe you can include the start date and an update date in a copyright statement (c) 2001-2023 when the work has been altered. The correct time to do this would probably be on commit, but that would be horrible.

Long story short, I think this is much better.