MDL-54641 enrol: fix trailing whitespace in upgrade.txt

enrol/upgrade.txt

@@ -6,7 +6,7 @@ information provided here is intended especially for developers.
 * core_enrol_external::get_enrolled_users now supports two additional parameters for ordering: sortby and sortdirection.
 * Enrolment plugins UI have been consolidated. Plugins can implement use_standard_editing_ui() function
   and add edit_instance_form() and edit_instance_validation() methods instead of providing their own edit.php and form.
-  They can then rely on the default implementation of get_action_icons and get_course_navigation. In future this will 
+  They can then rely on the default implementation of get_action_icons and get_course_navigation. In future this will
   mean they can be called by webservices/user upload tools because they can validate their data.
 
 === 3.0 ===