sim: Remove extra blank line

Remove an extra blank line from this file.

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/sim/src/lib.rs b/sim/src/lib.rs
index 6cea000..c5aa04f 100644
--- a/sim/src/lib.rs
+++ b/sim/src/lib.rs
@@ -229,4 +229,3 @@
         self.failures
     }
 }
-