Pin graphql-parser to 0.2.1

The new combine version is not compiling on stable in CI.

Author: tomhoule

graphql_client_codegen/Cargo.toml

@@ -17,4 +17,4 @@ serde = "^1.0.78"
 serde_derive = "1.0"
 serde_json = "1.0"
 heck = "0.3"
-graphql-parser = "0.2.2"
+graphql-parser = "=0.2.0"