Clean warnings

tests/build_generated_code.rs

@@ -1,11 +1,10 @@
 use std::fs;
 use std::process::Command;
-use std::path::PathBuf;
 use roto::google::protobuf::descriptor::{
     FileDescriptorSet
 };
 use roto::google::protobuf::compiler::plugin::{
-    CodeGeneratorRequest, CodeGeneratorResponse, CodeGeneratorResponseBuilder, code_generator_response::{File, FileBuilder},
+    CodeGeneratorRequest,
 };
 
 #[test]