Upgrade to latest versions of futures crates (RUSTSEC-2020-0059)

Author: djc

tokio-imap/Cargo.toml

@@ -17,8 +17,8 @@ maintenance = { status = "passively-maintained" }
 
 [dependencies]
 bytes = "0.6"
-futures-util = "0.3.1"
-futures-sink = "0.3.1"
+futures-util = "0.3.8"
+futures-sink = "0.3.8"
 imap-proto = { version = "0.12", path = "../imap-proto" }
 nom = "6"
 pin-project = "1"