Bump async-stream from 0.2.1 to 0.3.0 (#278)

bridges/relays/ethereum/Cargo.toml

@@ -8,7 +8,7 @@ license = "GPL-3.0-or-later WITH Classpath-exception-2.0"
 [dependencies]
 ansi_term = "0.12"
 async-std = "1.6.2"
-async-stream = "0.2.0"
+async-stream = "0.3.0"
 async-trait = "0.1.36"
 backoff = "0.2"
 bp-currency-exchange = { path = "../../primitives/currency-exchange" }