Fix pieces of derive. (#374)

Author: tomusdrw

derive/Cargo.toml

@@ -1,6 +1,7 @@
 [package]
 authors = ["Parity Technologies <admin@parity.io>"]
 documentation = "https://docs.rs/jsonrpc-derive/"
+description = "High level, typed wrapper for `jsonrpc-core`"
 edition = "2018"
 homepage = "https://github.com/paritytech/jsonrpc"
 license = "MIT"
@@ -23,4 +24,4 @@ jsonrpc-tcp-server = { version = "10.0", path = "../tcp" }
 serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"
-compiletest_rs = { version = "*", features = ["stable"] }
+compiletest_rs = { version = "0.3", features = ["stable"] }