Fixed the "Delete" button in the "Edit" form

This was already fixed in 597226c
but somehow it was lost in the next commits and pull requests.

Resources/views/edit.html.twig

@@ -19,7 +19,7 @@
                     <i class="fa fa-save"></i> {{ 'entity.save_changes' | trans }}
                 </button>
 
-                <button onclick="document.getElementById('delete-form').submit()" class="btn btn-danger">
+                <button type="button" onclick="document.getElementById('delete-form').submit()" class="btn btn-danger">
                     <i class="fa fa-trash"></i> {{ 'entity.delete' | trans() }}
                 </button>