Show trace on UnknownFailure #1968

Job	Run time
Build Echidna on ubuntu-20.04	5m 48s
Build Echidna on macos-13	9m 18s
Build Echidna on windows-latest	12m 25s
Test with solc 0.4.25 on ubuntu-latest	4m 49s
Test with solc 0.5.7 on ubuntu-latest	3m 20s
Test with solc 0.6.12 on ubuntu-latest	3m 59s
Test with solc 0.7.5 on ubuntu-latest	4m 13s
Test with solc 0.4.25 on windows-latest	4m 23s
Test with solc 0.5.7 on windows-latest	4m 20s
Test with solc 0.6.12 on windows-latest	5m 37s
Test with solc 0.7.5 on windows-latest	5m 23s
	1h 3m 35s

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