Update jokob-sk graph_online_history.js

Depending on how many devices are contained in the list, the y-axis may contain floating point numbers. This does not make sense.

front/js/graph_online_history.js

@@ -2,6 +2,7 @@ function pia_draw_graph_online_history(pia_js_graph_online_history_time, pia_js_
         var xValues = pia_js_graph_online_history_time;
         new Chart("OnlineChart", {
           type: "bar",
+          scaleIntegersOnly: true,
           data: {
             labels: xValues,
             datasets: [{