Fix ruff formatting errors in test_citation_metadata.py

[Copilot]

Pre-commit CI was failing due to two ruff violations in tests/hyrax/test_citation_metadata.py.

Changes

• I001 (import sort): moved import tomllib before from pathlib import Path to satisfy isort ordering
• E501 (line length): split 139-char assertion message into multi-line form to stay within the 110-char limit

Code Quality

• I have read the Contribution Guide and agree to the Code of Conduct
• My code follows the code style of this project
• My code builds (or compiles) cleanly without any errors or warnings
• My code contains relevant comments and necessary documentation

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