[3.11] gh-111092: Make turtledemo run without default root enabled (GH-111093) (#111096)

gh-111092: Make turtledemo run without default root enabled (GH-111093)

Add missing 'root' argument to PanedWindow call.
Other root children already have it.
(cherry picked from commit b802882fb2bff8b431df661322908c07491f3ce7)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>