Update copyright headers

[domna]

This updates the copyright headers to 2024 as generated by nyaml2nxdl

[lukaspie]

Thanks for the update. Two things:

1. Is there a good reason why only our recent changes to the contributed classes received the new year? IIRC, NIAC has a routine to set the new finishing date for all classes.
2. We should make sure that we don't change the starting date for any of the existing classes (e.g. NXroot).

[domna]

Thanks for the update. Two things:

1. Is there a good reason why only our recent changes to the contributed classes received the new year? IIRC, NIAC has a routine to set the new finishing date for all classes.

Actually, I don't completely know. I guess this depends on whether nyaml2nxdl uses the commented version when it was generated from nxdl vs. is completely generated from scratch.
I think we should have a discussion sometime on how to handle this, because I think there are some strange design decisions in how nyaml2nxdl handles this.

2. We should make sure that we don't change the starting date for any of the existing classes (e.g. NXroot).

The starting dates are already changed in our repository for some files. I don't know the latest status of the copyright discussion. This PR just updates the current year as generated by nyaml2nxdl to fix ci/cd for the whole repo.

My suggestion: We merge this to fix nxdl <-> nyaml ci/cd and open an issue on the general topic for later discussion. Sounds good?

[lukaspie]

Sounds good, you can merge this PR. I have created a new issues (#139) to keep track of the changed starting dates.

[lukaspie]

LGTM