system-prompt: Right align labels

Following https://developer.gnome.org/hig/stable/visual-layout.html.enSigned-off-by: Guido Günther <guido.gunther@puri.sm>

src/ui/system-prompt.ui

@@ -36,7 +36,7 @@
           <object class="GtkLabel" id="lbl_password">
             <property name="visible">True</property>
             <property name="can_focus">False</property>
-            <property name="halign">start</property>
+            <property name="halign">end</property>
             <property name="label" translatable="yes">Password:</property>
           </object>
           <packing>
@@ -66,7 +66,7 @@
           <object class="GtkLabel" id="lbl_confirm">
             <property name="visible">True</property>
             <property name="can_focus">False</property>
-            <property name="halign">start</property>
+            <property name="halign">end</property>
             <property name="label" translatable="yes">Confirm:</property>
           </object>
           <packing>