Sphinx 9 compatibility #524

Job	Run time
oorb-data / Download OpenOrb data for sbpy testing	7s
Python 3.11 with all optional dependencies (MacOS)	1s
tests / Load tox environments	7s
tests / Code style checks	23s
tests / Python 3.9 with oldest supported versions, measuring coverage	2m 6s
tests / Python 3.11 with all optional dependencies, measuring coverage	2m 6s
tests / Python 3.13 with minimal dependencies, measuring coverage	54s
	5m 44s

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