CI broke with 5.11.0 release

Our CI broke in the past 24 hours, which runs notebooks using nbconvert.

Looking at the logs, the only difference I see is that nbformat version 5.11.0 is now getting installed in the failing runs, versus 5.10.4 in the last successful run.

The error is the below (full log at https://github.com/microsoft/qdk/actions/runs/31200927144/job/92943561136#step:8:2077). Searching issues here, only #161 looks perhaps relevant in some way - but is an old issue.

I don't see any extra validation or breaking change in the changelog that should be causing new validation/failures in 5.11.0.

Happy to provide more details if needed.

    File "/opt/hostedtoolcache/Python/3.11.15/x64/lib/python3.11/site-packages/nbformat/validator.py", line 434, in validate
      _validate(nbdict, ref, version, version_minor, relax_add_props)
    File "/opt/hostedtoolcache/Python/3.11.15/x64/lib/python3.11/site-packages/nbformat/validator.py", line 486, in _validate
      raise error
  nbformat.validator.NotebookValidationError: {'targetProfile': 'unrestricted', 'manifest': '{\n    "dependencies": {\n        "Chemistry": {\n            "github": {\n                "ref": "v1.25.0",\n                "owner": "microsoft",\n                "repo": "qdk",\n                "path": "library/chemistry"\n            }\n        }\n    }\n}\n', 'projectRoot': 'file:///home/runner/work/qdk/qdk/samples/chemistry/SPSA'} is not valid under any of the given schemas
  
  Failed validating 'oneOf' in notebook['properties']['data']['additionalProperties']:
  
  On instance['data']['application/x.qsharp-config']:
  {'manifest': '{\n'
               '    "dependencies": {\n'
               '        "Chemistry": {\n'
               '            "gith...',
   'projectRoot': 'file:///home/runner/work/qdk/qdk/samples/chemistry/SPSA',
   'targetProfile': 'unrestricted'}