Fix course template for free course

apps/course/templates/course/course.html

@@ -25,7 +25,7 @@
         </div>
         <div class="go__title">Вернуться</div>
       </a>
-      {% if not paid %}
+      {% if not paid and course.price %}
       <a
         class="go__btn btn{% if pending %} btn_gray{% endif %} btn_md"
         {% if user.is_authenticated %}
@@ -387,7 +387,7 @@
           <div class="meta__title">{{ course.price|floatformat:"-2" }}₽</div>
         </div>
       </div>
-      {% if not paid %}
+      {% if not paid and course.price %}
       <a
         class="go__btn btn{% if pending %} btn_gray{% endif %} btn_md"
         {% if user.is_authenticated %}