move dev-dep to dep

As a workaround for rust-lang/cargo#6915

Author: vherbert

Cargo.toml

@@ -22,10 +22,11 @@ rand = { version = "0.7" }
 sha2 = { version = "0.9" }
 subtle = { version = "2.4", default-features = false }
 zeroize = { version = "1", default-features = false, features = ["zeroize_derive"] }
+ed25519-dalek = { version = "1", default-features = false }
 
 [dev-dependencies]
 criterion = { version = "0.3" }
-ed25519-dalek = { version = "1", default-features = false }
+
 
 [[bench]]
 name = "dalek_benchmarks"