update cargo_metadata

Author: wmorgue

Cargo.lock

@@ -12,7 +12,7 @@ build = "build.rs"
 [dependencies]
 # cargo hash delivered with nightly-2018-02-01
 cargo = { git = "https://github.com/rust-lang/cargo", rev = "1d6dfea44f97199d5d5c177c7dadcde393eaff9a" }
-cargo_metadata = "0.4"
+cargo_metadata = "0.5.2"
 env_logger = "0.5"
 failure = "0.1.1"
 jsonrpc-core = "8.0.1"