ci: guard compio is compatible with stable rust #350

Job	Run time
test (nightly, ubuntu-20.04)	1m 42s
test (nightly, ubuntu-22.04, io-uring-sqe128,io-uring-cqe32,io-uring-socket)	1m 39s
test (nightly, ubuntu-20.04, polling, true)	1m 44s
test (nightly, ubuntu-22.04, polling, true)	1m 41s
test (nightly, ubuntu-20.04, polling,native-tls, true)	1m 45s
test (nightly, ubuntu-22.04, polling,native-tls, true)	1m 49s
test (nightly, windows-latest, x86_64-pc-windows-msvc)	3m 48s
test (nightly, windows-latest, x86_64-pc-windows-gnu)	3m 22s
test (nightly, windows-latest, i686-pc-windows-msvc)	3m 40s
test (nightly, windows-latest, x86_64-pc-windows-msvc, iocp-global)	3m 8s
test (nightly, macos-12)	2m 41s
test (nightly, macos-13)	2m 36s
test (nightly, macos-14)	1m 19s
test (stable, ubuntu-20.04)	2m 18s
test (stable, ubuntu-22.04, io-uring-sqe128,io-uring-cqe32,io-uring-socket)	1m 59s
test (stable, ubuntu-20.04, polling, true)	2m 3s
test (stable, ubuntu-22.04, polling, true)	2m 2s
test (stable, ubuntu-20.04, polling,native-tls, true)	2m 10s
test (stable, ubuntu-22.04, polling,native-tls, true)	2m 6s
test (stable, windows-latest, x86_64-pc-windows-msvc)	4m 39s
test (stable, windows-latest, x86_64-pc-windows-gnu)	4m 1s
test (stable, windows-latest, i686-pc-windows-msvc)	4m 58s
test (stable, windows-latest, x86_64-pc-windows-msvc, iocp-global)	5m 21s
test (stable, macos-12)	2m 5s
test (stable, macos-13)	3m 12s
test (stable, macos-14)	1m 15s
	1h 9m 3s

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