lowest_passing_grade fix

lms/templates/dashboard.html

@@ -249,7 +249,7 @@
             % elif cert_status['status'] in ('generating', 'ready', 'notpassing'):
                   <p class="message-copy">Your final grade:
                             <span class="grade-value">${cert_status['grade']}</span>,
-                            grade required for certificate: ${course.lowest_passing_grade()}.</p>
+                            grade required for certificate: ${course.lowest_passing_grade}.</p>
             % endif
 
             % if cert_status['show_disabled_download_button'] or cert_status['show_download_url'] or cert_status['show_survey_button']: