Condense docstring for UnresolvedMarkerWarning #1323

Job	Run time
Run tests with coverage	2m 52s
Run tests with different pydantic versions	3m 28s
Run tests (3.9)	1m 49s
Run tests (3.8)	1m 52s
Run tests (3.12)	1m 52s
Run tests (3.10)	1m 50s
Run linters (flake8)	1m 28s
Run tests (3.13)	2m 3s
Run linters (pylint)	1m 38s
Run linters (mypy)	1m 40s
Run tests (3.11)	1m 50s
Run linters (pydocstyle)	1m 38s
	24m 0s

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