Update to socket2 v0.6 (#77)

Author: Thomasdezeeuw

Cargo.toml

@@ -25,7 +25,7 @@ async-std = { version = "1.13.0", optional = true, features = ["io_safety"] }
 # Optionally depend on tokio to implement traits for its types.
 tokio = { version = "1.6.0", features = ["io-std", "fs", "net", "process"], optional = true }
 # Optionally depend on socket2 to implement traits for its types.
-socket2 = { version = "0.5.0", optional = true }
+socket2 = { version = "0.6.0", optional = true }
 # Optionally depend on mio to implement traits for its types.
 mio = { version = "0.8.0", features = ["net", "os-ext"], optional = true }