Update tokio-tls requirement from 0.2.0 to 0.3.1

Updates the requirements on [tokio-tls](https://github.com/tokio-rs/tokio) to permit the latest version.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](https://github.com/tokio-rs/tokio/commits)

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -23,7 +23,7 @@ url = "1.0"
 rand = "0.6.1"
 futures = { version = "0.1", optional = true }
 tokio-io = { version = "0.1", optional = true }
-tokio-tls = { version = "0.2.0", optional = true }
+tokio-tls = { version = "0.3.1", optional = true }
 tokio-tcp = { version = "0.1", optional = true }
 tokio-codec = { version = "0.1", optional = true }
 tokio-reactor = { version = "0.1", optional = true }

websocket-base/Cargo.toml

@@ -26,7 +26,7 @@ futures = { version = "0.1", optional = true }
 native-tls = { version = "0.2.1", optional = true }
 tokio-codec = { version = "0.1", optional = true }
 tokio-io = { version = "0.1", optional = true }
-tokio-tls = { version = "0.2.0", optional = true }
+tokio-tls = { version = "0.3.1", optional = true }
 tokio-tcp = { version = "0.1", optional = true }
 
 [dev-dependencies.tokio]