test

switch back to processpoolexecutor #1758

Job	Run time
ubuntu-latest - 3.9	5m 58s
ubuntu-latest - 3.10	6m 0s
ubuntu-latest - 3.11	6m 35s
ubuntu-latest - 3.12	7m 5s
ubuntu-latest - 3.13	7m 4s
ubuntu-latest - 3.13-dev free-threading	8m 15s
ubuntu-latest - 3.14-dev	7m 5s
ubuntu-latest - 3.14-dev free-threading	8m 23s
ubuntu-latest - pypy-3.10	8m 31s
ubuntu-latest - pypy-3.9	7m 59s
macos-latest - 3.13	5m 42s
windows-latest - 3.13	10m 13s
	1h 28m 50s

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