Use latest cabal master for haddocks generation. Fix broken haddocks. #3054

Job	Run time
build (3.10.2.0, 9.6.4, macos-latest, bash)	3m 35s
build (8.10.7, 3.10.2.0, ubuntu-latest, bash)	3m 34s
build (8.10.7, 3.10.2.0, windows-latest, C:/msys64/usr/bin/bash.exe -e {0})	3m 30s
build (9.6.4, 3.10.2.0, ubuntu-latest, bash)	3m 33s
build (9.6.4, 3.10.2.0, windows-latest, C:/msys64/usr/bin/bash.exe -e {0})	3m 32s
build (9.8.1, 3.10.2.0, ubuntu-latest, bash)	3m 35s
build (9.8.1, 3.10.2.0, windows-latest, C:/msys64/usr/bin/bash.exe -e {0})	3m 31s
build-complete	1s
release	0s
	24m 51s

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