librem5: shell: Make the notification box vetical

This helps it work well on mobile but not on desktops.

src/gnome-software.ui

@@ -262,7 +262,7 @@
                 <property name="valign">GTK_ALIGN_START</property>
                 <child>
                   <object class="GtkBox">
-                    <property name="orientation">horizontal</property>
+                    <property name="orientation">vertical</property>
                     <property name="spacing">6</property>
                     <property name="visible">True</property>
                     <style>
@@ -272,6 +272,7 @@
                       <object class="GtkLabel" id="label_events">
                         <property name="visible">True</property>
                         <property name="halign">start</property>
+                        <property name="justify">center</property>
                         <property name="label">Some Title</property>
                         <property name="wrap">True</property>
                         <property name="wrap_mode">word-char</property>
@@ -285,7 +286,7 @@
                     </child>
                     <child>
                       <object class="GtkButtonBox">
-                        <property name="layout_style">end</property>
+                        <property name="layout_style">expand</property>
                         <property name="visible">True</property>
                         <child>
                           <object class="GtkButton" id="button_events_sources">