Update python-socketpool to version 0.5.3 / rev 16 via SR 953746
https://build.opensuse.org/request/show/953746
by user mcepl + dimstar_suse
- Add 37-python39.patch (gh#benoitc/socketpool#37) to make code
Python 3.9 compatible.
- Add port_to_py3k.patch (gh#benoitc/socketpool#38) porting tests
to py3k.
- 2to3 module is not required for build