testBusinessTemplateTwoFileExport: Since 1cbed531, output_encoding was not explicitly set.

This was still working with Zope 2.13 because the default output_encoding for
HTML was iso-8859-15 but this is not the case anymore with Zope 4. Moreover this
should be explicit rather than implicit anyway...

product/ERP5/tests/testBusinessTemplateTwoFileExport.py

@@ -1082,6 +1082,8 @@ AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO
                          "output_encoding": "iso-8859-15"}
     skin_folder._setObject(page_template_id, ZopePageTemplate(
       page_template_id, page_template_text, page_template_kw["content_type"]))
+    skin_folder._getOb(page_template_id).manage_changeProperties(
+      output_encoding=page_template_kw["output_encoding"])
 
     self.template.edit(template_skin_id_list=[skin_folder_id+'/'+page_template_id,])