erp5_wechat_secure_payment: Add UNITTEST mode as an option on the test

bt5/erp5_wechat_secure_payment/SkinTemplateItem/portal_skins/erp5_wechat_secure_payment/WechatService_view/my_wechat_mode.xml

@@ -243,6 +243,10 @@
                           <string>PRODUCTION</string>
                           <string>PRODUCTION</string>
                         </tuple>
+                        <tuple>
+                          <string>UNITTEST</string>
+                          <string>UNITTEST</string>
+                        </tuple>
                       </list>
                     </value>
                 </item>