Bump intersphinx base for Python docs to 3.13 #1864

Job	Run time
Lint	4s
Run tests (3.8)	7s
Run tests (3.8.0)	11s
Run tests (3.9)	6s
Run tests (3.9.0)	15s
Run tests (3.10)	8s
Run tests (3.10.0)	12s
Run tests (3.11)	6s
Run tests (3.11.0)	16s
Run tests (3.12)	12s
Run tests (3.12.0)	13s
Run tests (3.13)	8s
Run tests (3.13.0)	18s
Run tests (pypy3.8)	6s
Run tests (pypy3.9)	10s
Run tests (pypy3.10)	7s
Create an issue if daily tests failed	0s
	2m 39s

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