Bump proptest from 1.5.0 to 1.6.0 #379

Job	Run time
docs-pr	2s
spell check with typos	4s
build-on-windows (windows-debug)	44s
build-on-linux (linux-kvm-debug)	51s
build-on-linux (linux-kvm-release)	49s
build-on-windows (windows-release)	39s
build-on-linux (linux-hyperv-debug)	59s
build-on-linux (linux-hyperv-release)	56s
fuzzing / fuzz	8m 49s
rust / build (hyperv, amd, debug)	13m 49s
rust / build (hyperv, amd, release)	20m 27s
rust / build (hyperv, intel, debug)	14m 16s
rust / build (hyperv, intel, release)	19m 35s
rust / build (mshv, amd, debug)	10m 5s
rust / build (mshv, amd, release)	12m 40s
rust / build (mshv, intel, debug)	8m 49s
rust / build (mshv, intel, release)	12m 17s
rust / build (kvm, amd, debug)	9m 29s
rust / build (kvm, amd, release)	12m 47s
rust / build (kvm, intel, debug)	8m 31s
rust / build (kvm, intel, release)	12m 33s
	2h 49m 11s

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