[manager] reduce default width for packages view

resources/manager_window.ui

@@ -365,7 +365,7 @@
                         <property name="can_focus">False</property>
                         <child>
                           <object class="GtkScrolledWindow" id="packages_scrolledwindow">
-                            <property name="width_request">700</property>
+                            <property name="width_request">500</property>
                             <property name="height_request">200</property>
                             <property name="visible">True</property>
                             <property name="can_focus">True</property>