Upgrade build to GHC 9.6 #2009

Job	Run time
Build Echidna on ubuntu-20.04	22m 58s
Build Echidna on macos-13	37m 31s
Build Echidna on windows-latest	26m 25s
Test with solc 0.4.25 on ubuntu-latest	4m 46s
Test with solc 0.5.7 on ubuntu-latest	3m 28s
Test with solc 0.6.12 on ubuntu-latest	3m 31s
Test with solc 0.7.5 on ubuntu-latest	3m 19s
Test with solc 0.4.25 on windows-latest	4m 10s
Test with solc 0.5.7 on windows-latest	4m 1s
Test with solc 0.6.12 on windows-latest	4m 25s
Test with solc 0.7.5 on windows-latest	5m 26s
	2h 0m 0s

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