Update src/npm.rs

Author: rafaelbeckel

src/npm.rs

@@ -20,7 +20,7 @@ pub fn npm_pack(path: &str) -> Result<()> {
 pub fn npm_publish(path: &str, access: Option<Access>, tag: Option<String>) -> Result<()> {
     let mut cmd = child::new_command("npm");
     match access {
-        Some(a) => cmd.current_dir(path).arg("publish").arg(a.to_string()),
+        Some(a) => cmd.current_dir(path).arg("publish").arg(&a.to_string()),
         None => cmd.current_dir(path).arg("publish"),
     };
     if let Some(tag) = tag {