[IMP] google_spreadsheet: Add widget="url" to the URL field on tree view

Users can now click this field, instead of having Odoo open the Form View to click it.

Benefits:
1. Saves the user from clicking TWICE (they only have to click ONCE with this PR)
2. Keeps the list view of all spreadsheets open (user has to GO BACK to see the list without this PR)

addons/google_spreadsheet/views/google_spreadsheet_views.xml

@@ -9,7 +9,7 @@
             <field name="arch" type="xml">
                 <tree string="Google Spreadsheets">
                     <field name="name" string="Name"/>
-                    <field name="url" />
+                    <field name="url" widget="url" />
                 </tree>
             </field>
         </record>
@@ -64,4 +64,4 @@
             parent="base.menu_board_root"
             action="action_ir_attachment_google_spreadsheet_tree"/>
 
-</odoo>
+</odoo>