Fix build issue with bitvec/funty

See:

https://github.com/bitvecto-rs/bitvec/issues/105

Signed-off-by: Sean Young <sean@mess.org>

Cargo.toml

@@ -44,6 +44,7 @@ base58 = "0.1.0"
 sha2 = "0.9"
 ripemd160 = "0.9"
 bitvec = "0.20"
+funty = "=1.1.0"
 itertools = "0.10"
 
 [dev-dependencies]