Update sphinx from 6.2.1 to 7.2.6 #963

Job	Run time
conda (ubuntu-latest, ci/py38-env.yml)	1h 48m 35s
conda (ubuntu-latest, ci/py39-env.yml)	10m 54s
conda (ubuntu-latest, ci/py310-env.yml)	8m 54s
conda (macos-latest, ci/py38-env.yml)	23m 26s
conda (macos-latest, ci/py39-env.yml)	10m 19s
conda (macos-latest, ci/py310-env.yml)	10m 11s
conda (windows-latest, ci/py38-env.yml)	9m 5s
conda (windows-latest, ci/py39-env.yml)	13m 41s
conda (windows-latest, ci/py310-env.yml)	14m 54s
	3h 29m 59s

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