Add rust-bitcoin devs to authors

In preparation for attempting to stabilise this library add "the
rust-bitcoin developers" to the authors. This is both for attribution
and to accept responsibility if we do anything wrong.

Author: tcharding

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "bech32"
 version = "0.9.1"
-authors = ["Clark Moody"]
+authors = ["Clark Moody", "The rust-bitcoin developers"]
 repository = "https://github.com/rust-bitcoin/rust-bech32"
 description = "Encodes and decodes the Bech32 format"
 readme = "README.md"