Merge rust-bitcoin/rust-bitcoin#1013: Do not pin transitive ryu dependency

553a681 Do not pin transitive ryu dependency (Tobin C. Harding)

Pull request description:

  We do not need to pin the `ryu` transitive dependency now that MSRV is not 1.29.

ACKs for top commit:
  apoelstra:
    ACK 553a681
  Kixunil:
    ACK 553a681

Tree-SHA512: 072a2fea39a0405424579e0e34603f27f12a5271a8979d6f9204b3114827b2c1931105df418ccb5071b641a108b7db803eec953ced04a670509d21652c6a6ca4

Author: apoelstra

Cargo.toml

@@ -50,8 +50,6 @@ serde_json = "<1.0.45"
 serde_test = "1"
 secp256k1 = { version = "0.22.0", features = [ "recovery", "rand-std" ] }
 bincode = "1.3.1"
-# We need to pin ryu (transitive dep from serde_json) to stay compatible with Rust 1.22.0
-ryu = "<1.0.5"
 
 [[example]]
 name = "bip32"