Add CITATION.cff according to zenodo record

[white-gecko]

Add CITATION.cff according to https://zenodo.org/record/7771749.

Close #2059.

Summary of changes

Add the CITATION.cff file according to the spec https://citation-file-format.github.io/ and with the data of https://zenodo.org/record/7771749 and orcids added manually, left out in doubt.

Checklist

• Checked that there aren't other open pull requests for
  the same change.
• Checked that all tests and type checking passes.
• If the change adds new features or changes the RDFLib public API:
  • Created an issue to discuss the change and get in-principle agreement. -> exists already: Create a CITATION.cff file #2059
  • Considered adding an example in ./examples.
• If the change has a potential impact on users of this project:
• Considered granting push permissions to the PR branch,
  so maintainers can fix minor issues and keep your PR up to date.

[coveralls]

coverage: 90.924%. remained the same when pulling 642c3f1 on white-gecko:feature/addcitationcff into 5ee8bd7 on RDFLib:main.

[aucampia]

Looks good, I will add a note in the release that if someone that contributed and is not listed in here wants their details included they can make a PR, and it will be in the next release.