convert input to button

devices/templates/devices/warranty_create.html

@@ -7,7 +7,7 @@
 <form method="post">
     {% csrf_token %}
     {{ form|crispy }}
-    <input type="submit" value="Save" class="btn btn-primary">
+    <button type="submit" class="btn btn-primary">Save</button>
 </form>
 </div>
 {% endblock %}