Use Tornado's selector thread on Windows/asyncio/ProactorEventLoop #3183

Job	Run time
check_release	32s
build (ubuntu-latest, 3.9)	34s
build (ubuntu-latest, 3.10)	35s
link_check	37s
build (ubuntu-latest, 3.11)	35s
build (ubuntu-latest, 3.12)	34s
Make SDist	22s
build (ubuntu-latest, 3.13)	35s
build (ubuntu-latest, pypy-3.9)	36s
build (ubuntu-latest, pypy-3.10)	35s
test_docs	30s
build (windows-latest, 3.9)	28s
build (windows-latest, 3.10)	21s
Test Lint	37s
build (windows-latest, 3.11)	27s
build (windows-latest, 3.12)	26s
Test Minimum Versions	36s
build (windows-latest, 3.13)	27s
build (windows-latest, pypy-3.9)	33s
build (windows-latest, pypy-3.10)	33s
Test Prereleases	38s
build (macos-latest, 3.9)	25s
test_without_debugpy (ubuntu-latest, 3.9)	26s
build (macos-latest, 3.10)	26s
build (macos-latest, 3.11)	40s
build (macos-latest, 3.12)	36s
build (macos-latest, 3.13)	36s
build (macos-latest, pypy-3.9)	37s
build (macos-latest, pypy-3.10)	37s
Install from SDist and Test	1s
coverage	1s
	15m 36s

Provide feedback