added decimal format variable for invoice duration (#1037)

templates/invoice/index.html.twig

@@ -45,7 +45,7 @@
             {% set duration = entry.duration|duration %}
             {% if entry.fixedRate is not null %}
                 {% set rate = entry.fixedRate %}
-                {% set duration = 1 %}
+                {% set duration = 1 %}{# FIXME fixed rates #}
             {% elseif entry.hourlyRate is not null %}
                 {% set rate = entry.hourlyRate %}
             {% else %}