Add PartialEq and Eq implementations for Span
diff --git a/src/lib.rs b/src/lib.rs
index d49af0c..1d9f0cf 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -153,7 +153,7 @@
     pub column: usize,
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, PartialEq, Eq)]
 pub struct Span(imp::Span);
 
 impl Span {