fix(client): panic when pool idle timeout set to zero #2227

Job	Run time
Verify hyper.h is up to date	50s
Check Style	9s
features	2m 37s
Test with Miri	1m 52s
Check deprecated on stable	34s
Test C API (FFI)	1m 9s
Check deprecated on beta	39s
Check MSRV (1.63)	4m 31s
Test stable on ubuntu-latest	2m 54s
Test stable on windows-latest	6m 7s
Test stable on macOS-latest	3m 55s
Test beta on ubuntu-latest	3m 8s
Test beta on windows-latest	5m 5s
Test beta on macOS-latest	4m 5s
Test nightly on ubuntu-latest	3m 19s
Test nightly on windows-latest	5m 49s
Test nightly on macOS-latest	4m 24s
Build docs	34s
CI is green	3s
	51m 44s

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