bpo-33479: Remove unqualified tkinter threadsafe claim. (GH-6990)


It has not been true for several years and likely never was.
(cherry picked from commit 6b37d0d5300813de31d66df1c77dad7e1027e4d8)

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