[gnome-calendar] window: Switch to HdyHeaderBar

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit ac4667133477012081593e5e302508cb1d44096a
Author: Evangelos Ribeiro Tzaras <devrtz fortysixandtwo eu>
Date:   Wed Sep 16 14:24:02 2020 +0200

    window: Switch to HdyHeaderBar
    
    Change the headerbar to HdyHeaderBar

 src/gui/gcal-window.ui | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/gui/gcal-window.ui b/src/gui/gcal-window.ui
index daf1009b..9f4483b7 100644
--- a/src/gui/gcal-window.ui
+++ b/src/gui/gcal-window.ui
@@ -164,7 +164,7 @@
           </packing>
         </child>
         <child>
-          <object class="GtkHeaderBar" id="header_bar">
+          <object class="HdyHeaderBar" id="header_bar">
             <property name="visible">True</property>
             <property name="show_close_button">True</property>
             <property name="title" translatable="yes">Calendar</property>