[FIX] stock_sms: Change class of disable sms button

Change class of disable sms button in secondary

task-id: 2070836

addons/stock_sms/wizard/confirm_stock_sms_views.xml

@@ -15,7 +15,7 @@
                     <button name="send_sms" type="object"
                             string="Confirm" class="oe_highlight"/>
                     <button name="dont_send_sms" type="object"
-                            string="Disable SMS" class="oe_highlight"/>
+                            string="Disable SMS" class="btn btn-secondary"/>
                     <button special="cancel" string="Cancel"/>
                 </footer>
             </form>