[niepce] rust: Use dyn for Trait objects

[Hubert Figuière <hub src gnome org>]

commit f1afe9e8ceee925453fe5c4e17449ae10da1bbd0
Author: Hubert Figuière <hub figuiere net>
Date:   Thu Sep 26 23:56:46 2019 -0400

    rust: Use dyn for Trait objects

 src/engine/library/op.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/engine/library/op.rs b/src/engine/library/op.rs
index 0bd652d..f444d3c 100644
--- a/src/engine/library/op.rs
+++ b/src/engine/library/op.rs
@@ -1,7 +1,7 @@
 /*
  * niepce - engine/library/op.rs
  *
- * Copyright (C) 2017 Hubert Figuière
+ * Copyright (C) 2017-2019 Hubert Figuière
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -22,7 +22,7 @@ use std::sync::Arc;
 use engine::db::Library;
 
 // When we can use a FnOnce here, we should.
-type Function = Fn(&Library) -> bool + Send + Sync + 'static;
+type Function = dyn Fn(&Library) -> bool + Send + Sync + 'static;
 
 pub struct Op {
     op: Arc<Function>