[ADD] do not show registration link if state not OK

templates/training_page.xml

@@ -107,8 +107,13 @@
                         </t>
                     </div>
                 </div>
-                <div class="training-right-block">
-                    <a t-attf-href="#{training.registration_survey_id.get_start_url()}" class="btn btn-secondary" name="but_training_registration">Inscription</a>
+                <div name="div_training_button" class="training-right-block" t-if="training.state in ['2_broadcast', '3_confirmed']">
+                    <a
+                        t-attf-href="#{training.registration_survey_id.get_start_url()}"
+                        class="btn btn-secondary"
+                        name="but_training_registration">
+                        Inscription
+                    </a>
                 </div>
             </div>
         </div>