improved invoice handling for fixed rates (#1058)

templates/invoice/renderer/freelancer.html.twig

@@ -80,7 +80,7 @@
                     {% set duration = entry.duration|duration %}
                     {% if entry.fixedRate is not null %}
                         {% set rate = entry.fixedRate %}
-                        {% set duration = 1 %}{# FIXME fixed rates #}
+                        {% set duration = entry.amount %}
                     {% elseif entry.hourlyRate is not null %}
                         {% set rate = entry.hourlyRate %}
                     {% else %}