[gnome-boxes] preferences, snapshot-row: Use "flat" style for actions button

[Felipe Borges <felipeborges src gnome org>]

commit e41655f25eb2561af18f7d573e8c289019fa5805
Author: Felipe Borges <felipeborges gnome org>
Date:   Thu Dec 16 17:12:17 2021 +0100

    preferences, snapshot-row: Use "flat" style for actions button

 data/ui/preferences/snapshot-list-row.ui | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/data/ui/preferences/snapshot-list-row.ui b/data/ui/preferences/snapshot-list-row.ui
index a2608dcd..5c316d6e 100644
--- a/data/ui/preferences/snapshot-list-row.ui
+++ b/data/ui/preferences/snapshot-list-row.ui
@@ -55,7 +55,7 @@
                 <property name="margin_bottom">4</property>
                 <property name="margin_end">4</property>
                 <style>
-                  <class name="image-button" />
+                  <class name="flat" />
                 </style>
                 <child>
                   <object class="GtkImage">