Revert "Bump async-std from 1.5.0 to 1.6.0" (#127)

* Revert "Bump async-std from 1.5.0 to 1.6.0 (#126)"

This reverts commit 3c15a65929447a12aa23c1f34c9b783d117deed2.

* Add async-std=1.6 to ignore.

bridges/relays/ethereum/Cargo.toml

@@ -6,7 +6,7 @@ edition = "2018"
 
 [dependencies]
 ansi_term = "0.12"
-async-std = "=1.6.0"
+async-std = "=1.5.0"
 async-stream = "0.2.0"
 async-trait = "0.1.33"
 clap = { version = "2.33.1", features = ["yaml"] }

bridges/relays/substrate/Cargo.toml

@@ -5,7 +5,7 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"
 
 [dependencies]
-async-std = "=1.6.0"
+async-std = "=1.5.0"
 clap = "2.33.1"
 ctrlc = "3.1.4"
 derive_more = "0.99.7"