Create conda env for sphinx #33

Job	Run time
build_linux (3.8)	8m 25s
build_linux (3.9)	6m 16s
build_linux (3.10)	5m 48s
build_windows (3.8)	14m 10s
build_windows (3.9)	16m 4s
build_windows (3.10)	9m 49s
test_linux (3.8, true, ubuntu-20.04)	1m 22s
test_linux (3.9, true, ubuntu-20.04)	1m 22s
test_linux (3.10, true, ubuntu-20.04)	1m 31s
upload_linux	0s
test_windows (3.8, false, windows-latest)	6m 5s
test_windows (3.9, false, windows-latest)	6m 12s
test_windows (3.10, false, windows-latest)	4m 59s
upload_windows	0s
	1h 22m 3s

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