fix: add lifetime annotation (clippy)

src/backups.rs

@@ -180,7 +180,7 @@ impl Backup {
         &self.name
     }
 
-    pub fn device<'a>(&'a self, devices: &'a [Device]) -> Option<&Device> {
+    pub fn device<'a>(&'a self, devices: &'a [Device]) -> Option<&'a Device> {
         devices.iter().find(|dev| dev.name() == self.device)
     }
 

src/storages/directory.rs

@@ -127,7 +127,7 @@ impl StorageExt for Directory {
     }
 
     // Get parent `&Storage` of directory.
-    fn parent<'a>(&'a self, storages: &'a Storages) -> Option<&Storage> {
+    fn parent<'a>(&'a self, storages: &'a Storages) -> Option<&'a Storage> {
         storages.get(&self.parent)
     }
 }