Bug#937452: Bug#936307: claws-mail: Python2 removal in sid/bullseye

[Matthias Klose]

Control: tags -1 - moreinfo
Control: severity -1 serious

No need for more info. According to
https://lists.debian.org/debian-gtk-gnome/2019/10/msg00001.html
pygtk will be removed in bullseye.