adds translation string for error when leaving a conversation

Author: Kneeba921

app/models/better_together/conversation.rb

@@ -19,7 +19,7 @@ def to_s
     def at_least_one_participant
       return unless participants.empty?
 
-      errors.add(:conversation_participants, 'You cannot remove the last participant from a conversation')
+      errors.add(:conversation_participants, t('pundit.errors.leave_conversation'))
     end
   end
 end

config/locales/en.yml

@@ -1502,6 +1502,7 @@ en:
       destroy: You are not authorized to delete this %{resource}.
       edit: You are not authorized to edit this %{resource}.
       index: You are not authorized to view the list of %{resource}.
+      leave_conversation: You are the final conversation participant and cannot leave
       new: You are not authorized to create a new %{resource}.
       show: You are not authorized to view this %{resource}.
       update: You are not authorized to update this %{resource}.

config/locales/es.yml

@@ -1490,6 +1490,7 @@ es:
       destroy: No está autorizado para eliminar este %{resource}.
       edit: No está autorizado para editar este %{resource}.
       index: No está autorizado para ver la lista de %{resource}.
+      leave_conversation: You are the final conversation participant and cannot leave
       new: No está autorizado para crear un nuevo %{resource}.
       show: No está autorizado para ver este %{resource}.
       update: No está autorizado para actualizar este %{resource}.

config/locales/fr.yml

@@ -1512,6 +1512,7 @@ fr:
       destroy: Vous n'êtes pas autorisé à supprimer ce %{resource}.
       edit: Vous n'êtes pas autorisé à modifier ce %{resource}.
       index: Vous n'êtes pas autorisé à consulter la liste des %{resource}.
+      leave_conversation: You are the final conversation participant and cannot leave
       new: Vous n'êtes pas autorisé à créer un nouveau %{resource}.
       show: Vous n'êtes pas autorisé à consulter ce %{resource}.
       update: Vous n'êtes pas autorisé à mettre à jour ce %{resource}.