Increased minimum size for disconnect window

ubl-settings-system-domain.glade

@@ -4,6 +4,8 @@
   <requires lib="gtk+" version="3.24"/>
   <!-- interface-css-provider-path ubl-settings-system.css -->
   <object class="GtkApplicationWindow" id="MainWindow">
+    <property name="width-request">450</property>
+    <property name="height-request">300</property>
     <property name="can-focus">False</property>
     <property name="modal">True</property>
     <property name="icon-name">com.ublinux.ubl-settings-repomanager</property>