[FIX] Ensure np namespace URL has trailing /

[alyssadai]

Changes proposed in this pull request:

• Previously, since the np namespace URL did not have a trailing slash, pipeline name terms were appearing formatted in the graph as e.g.,: https://github.com/nipoppy/pipeline-catalog/tree/main/processingfmriprep, which is not ideal (interestingly, json-ld playground isn't even able to expand the term URI when the prefix URL lacks a trailing separator, it just stays as np:fmriprep)
• This PR regenerates the example JSONLD files to ensure the np URL ends with a /

Checklist

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• PR has an interpretable title with a prefix ([ENH], [FIX], [REF], [TST], [CI], [MNT], [INF], [MODEL], [DOC]) (see our Contributing Guidelines for more info)
• PR links to GitHub issue with mention Closes #XXXX
• Tests pass
• Checks pass

For new features:

• Tests have been added

For bug fixes:

• There is at least one test that would fail under the original bug conditions.

[rmanaem]

🧑‍🍳