defined_namespace_creator: concatenate several rdfs:comments

[HanKruiger]

Summary of changes

• FIxed a bug in defined_namespace_creator so that when a resource in an ontology is commented on multiple times (with e.g. rdfs:comment), it creates only a single class variable in the resulting DefinedNamespace where the Python comment is the concatenation of the rdfs:comments.

Checklist

• Checked that there aren't other open pull requests for
  the same change.
• Added tests for any changes that have a runtime impact.
• Checked that all tests and type checking passes.
• For changes that have a potential impact on users of this project:
  • [/] Updated relevant documentation to avoid inaccuracies.
  • [/] Considered adding additional documentation.
  • [/] Considered adding an example in ./examples for new features.
  • [/] Considered updating our changelog (CHANGELOG.md).
• Considered granting push permissions to the PR branch,
  so maintainers can fix minor issues and keep your PR up to date.

[aucampia]

thanks for the PR @HanKruiger, I will probably include this in the release that will go out shortly, but I will maybe make some small changes to your tests first. The change to the code itself looks 💯

[coveralls]

Coverage: 90.782%. Remained the same when pulling d74ccad on HanKruiger:main into 35a3537 on RDFLib:main.

[aucampia]

Thanks for this fix @HanKruiger, looks good to me. I just move your test data to a different location though, defined_namespaces are intended for well known externally defined namespaces/vocabularies/ontologies, we don't really have a good place for contrived test data, so I made test/data/contrived with a README.md to explain its purpose.

I will likely merge this later tonight.

[HanKruiger]

Cheers @aucampia! Thanks for the quick merge.