fix build with nightly

wez · wez · commit 0061aaa813e7 · 2018-12-12T09:07:10.000-08:00
diff --git a/src/lib.rs b/src/lib.rs
@@ -26,7 +26,6 @@
 
 extern crate either;
 extern crate xmltree;
-#[macro_use]
 extern crate failure;
 
 #[cfg(feature = "unproven")]
