fix building without 'inspect' feature

src/arg/parsing.rs

@@ -4,7 +4,7 @@ use std::collections::{HashMap, HashSet};
 use std::mem::Discriminant;
 use std::fmt;
 
-use config::OutputSerialisationMode;
+#[cfg(feature="inspect")] use config::OutputSerialisationMode;
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum Argument