PicoGraphics::polygon Y coordinate is offset by +1px

[di-cl]

Both calls listed below produce identical result (1px border along the perimeter of the pimoroni display pack 2.0), with PicoGraphics::polygon top Y coordinate offset by +1px.

• graphics.rectangle(Rect(1, 1, 318, 238))
• graphics.polygon({Point(1, 0), Point(318, 0), Point(318, 238), Point(1, 238)})