Bump bitcoin-bech32 dependency

This makes the Address::Payload::WitnessProgram inner type compatible
with rust-lightning-invoice's Fallback::SegWitProgram's inner type.
This allows specifying fallbacks from addresses.

Cargo.toml

@@ -21,7 +21,7 @@ unstable = []
 use-serde = ["serde", "bitcoin_hashes/serde"]
 
 [dependencies]
-bitcoin-bech32 = "0.8.0"
+bitcoin-bech32 = "0.9.0"
 byteorder = "1.2"
 rand = "0.3"
 bitcoin_hashes = "0.3"