tests(client): fix flaky pool test (#220) #686

Job	Run time
Check Style	15s
semver	20s
features	37s
Check MSRV (1.63)	4m 28s
Test with Miri	52s
Test beta on windows-latest	1m 16s
Test nightly on ubuntu-latest	34s
Test nightly on macos-latest	53s
Test stable on ubuntu-latest	34s
Test nightly on windows-latest	1m 30s
Test beta on macos-latest	52s
Test stable on macos-latest	36s
Test stable on windows-latest	2m 2s
Test beta on ubuntu-latest	38s
Build docs	18s
CI is green	2s
	15m 47s

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