Share one event loop per test module to stop Windows socketpair churn #3389

Job	Run time
checks / pre-commit	47s
checks / readme-snippets	15s
checks / docs	44s
checks / test (3.11, locked, ubuntu-latest)	1m 17s
checks / test (3.13, locked, windows-latest)	1m 54s
checks / test (3.11, lowest-direct, windows-latest)	2m 9s
checks / test (3.11, locked, windows-latest)	1m 44s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 30s
checks / test (3.12, locked, ubuntu-latest)	1m 44s
checks / test (3.10, locked, windows-latest)	2m 9s
checks / test (3.13, lowest-direct, windows-latest)	1m 53s
checks / test (3.14, lowest-direct, windows-latest)	1m 58s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 22s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 15s
checks / test (3.10, locked, ubuntu-latest)	1m 28s
checks / test (3.12, locked, windows-latest)	1m 58s
checks / test (3.10, lowest-direct, windows-latest)	1m 58s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 15s
checks / test (3.14, locked, windows-latest)	3m 2s
checks / test (3.12, lowest-direct, windows-latest)	1m 55s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 23s
checks / test (3.13, locked, ubuntu-latest)	1m 16s
checks / test (3.14, locked, ubuntu-latest)	2m 20s
all-green	3s
	37m 19s

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