Version bumped to v0.4.0

Author: tailhook

Cargo.toml

@@ -10,7 +10,7 @@ keywords = ["graphql", "parser"]
 categories = ["parser-implementations", "command-line-interface"]
 homepage = "https://github.com/graphql-rust/graphql-parser"
 documentation = "https://docs.rs/graphql-parser"
-version = "0.3.0"
+version = "0.4.0"
 authors = ["Paul Colomiets <paul@colomiets.name>"]
 edition = "2018"