Fuzz

Merge rust-bitcoin/rust-miniscript#646: Introduce an example binary u… #332

Job	Run time
fuzz (roundtrip_semantic)	4m 52s
fuzz (parse_descriptor)	4m 48s
fuzz (parse_descriptor_secret)	4m 58s
fuzz (roundtrip_miniscript_script)	4m 56s
fuzz (roundtrip_miniscript_str)	5m 26s
fuzz (roundtrip_descriptor)	4m 53s
fuzz (roundtrip_concrete)	4m 40s
fuzz (compile_descriptor)	5m 21s
verify-execution	7s
	40m 1s

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