update dependency (#295)

oracle/rpc/Cargo.toml

@@ -6,9 +6,9 @@ edition = "2018"
 
 [dependencies]
 codec = { package = "parity-scale-codec", version = "1.3.0" }
-jsonrpc-core = "14.0.5"
-jsonrpc-core-client = "14.0.5"
-jsonrpc-derive = "14.0.5"
+jsonrpc-core = "15.0.0"
+jsonrpc-core-client = "15.0.0"
+jsonrpc-derive = "15.0.0"
 sp-runtime = { version = "2.0.0" }
 sp-api = { version = "2.0.0" }
 sp-blockchain = { version = "2.0.0" }