Fix sphinx warnings #881

Job	Run time
linters (3.9, ubuntu-latest)	1m 6s
Testing on Python 3.8 (ubuntu-latest)	1m 5s
Testing on Python 3.8 (macos-13)	1m 24s
Testing on Python 3.8 (windows-2019)	2m 48s
Testing on Python 3.9 (ubuntu-latest)	1m 7s
Testing on Python 3.9 (macos-13)	1m 22s
Testing on Python 3.9 (windows-2019)	2m 2s
Testing on Python 3.10 (ubuntu-latest)	1m 4s
Testing on Python 3.10 (macos-13)	1m 23s
Testing on Python 3.10 (windows-2019)	2m 12s
Testing on Python 3.11 (ubuntu-latest)	1m 4s
Testing on Python 3.11 (macos-13)	1m 24s
Testing on Python 3.11 (windows-2019)	2m 36s
	20m 37s

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