Chart widget does not display the correct time zone in line mode

[David-Fabijan]

When using the char widget to display a line graph with time on the x axis, the chart always displays the time in GMT, no matter the current time zone set. I don't believe that is the desired behaviour.

An example can be seen here https://docs.getgrist.com/3uGYUy5NDtMS/Errorr-reporting?utm_id=share-doc

The last timestamp in the dataset is at 9:28 (when set to CET), but the last point on the graph is at 8:28. The graph does not change when you change the timezone settings.