Replace Tornado with AnyIO #1938

Job	Run time
test_docs	3m 16s
check_release	2m 18s
Test Lint	1m 26s
build (ubuntu-latest, 3.8)	4m 9s
build (ubuntu-latest, 3.11)	2m 56s
Test Minimum Versions	3m 51s
test_without_debugpy (ubuntu-latest, 3.9)	1m 49s
build (windows-latest, 3.8)	7m 46s
link_check	4m 17s
build (windows-latest, 3.11)	6m 29s
build (macos-latest, 3.8)	3m 58s
Test Prereleases	2m 10s
build (macos-latest, 3.11)	3m 48s
Make SDist	44s
build (windows-latest, 3.9)	7m 52s
build (ubuntu-latest, pypy-3.8)	7m 10s
build (macos-latest, 3.10)	3m 46s
Install from SDist and Test	2m 7s
coverage	0s
tests_check	2s
	1h 9m 54s

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