Unstable Notebook client tests - Metadata field is not in valid format

Frequently experiencing NotebookClient integration tests failing as part of GitHub Actions but recoverable on manual retry

=========================== short test summary info ============================
FAILED tests/integration/notebook/test_notebook_client.py::TestNotebookClient::test__update_existing_notebook_content__update_notebook_content_succeeds - nisystemlink.clients.core._api_exception.ApiException: Server responded with <400 Bad Request> (https://test-api.lifecyclesolutions.ni.com/ninotebook/v1/notebook).

name='Notebook.InvalidMetadataFormat' code=-252526 message='Metadata field is not in valid format.' args=[] resource_type=None resource_id=None inner_errors=[]
FAILED tests/integration/notebook/test_notebook_client.py::TestNotebookClient::test__query_notebook_by_id__return_notebook_matches_id - nisystemlink.clients.core._api_exception.ApiException: Server responded with <400 Bad Request> (https://test-api.lifecyclesolutions.ni.com/ninotebook/v1/notebook).

name='Notebook.InvalidMetadataFormat' code=-252526 message='Metadata field is not in valid format.' args=[] resource_type=None resource_id=None inner_errors=[]

Start with tests/integration/notebook/test_notebook_client.py and the two failing NotebookClient tests named in the report. Run them in GitHub Actions or locally and inspect the notebook metadata sent to https://test-api.lifecyclesolutions.ni.com/ninotebook/v1/notebook. Done means both tests pass reliably without manual retries and no longer receive Notebook.InvalidMetadataFormat.