Use a more generic way to use an hour formatter

scintillation/averaging.py

@@ -286,8 +286,8 @@ def make_plot(data_array, time_axis, frequency_axis, station_name, plot_full_pat
     ax.set_xlim(
         [datetime(year=datetime_axis[0].year, month=datetime_axis[0].month, day=datetime_axis[0].day,
                   hour=datetime_axis[0].hour),
-         datetime(year=datetime_axis[-1].year, month=datetime_axis[-1].month, day=(datetime_axis[-1].day + (datetime_axis[-1].hour + 1) // 24),
-                  hour=(datetime_axis[-1].hour + 1) % 24)]
+         datetime(year=datetime_axis[0].year, month=datetime_axis[0].month, day=datetime_axis[0].day,
+                  hour=datetime_axis[0].hour) + timedelta(hours=1)]
     )
     ax.set_xlabel('Time (UT)')
     ax.set_ylabel('Frequency (MHz)')