v3.20.0 Update

• "Progress Line" has been added to the Gantt chart.
• It is now possible to fix the display period of the Gantt chart.
• The calculation method for displaying the progress of parent task durations on the Gantt chart has been changed (progress for tasks without explicitly set deadlines is no longer included).
• Other layout adjustments and minor improvements, including a fix for an issue where project tasks were incorrectly displayed in the tray.