gcd in fractions removed from python 3.9

[designbynumbers]

When running the examples in python 3.10, one gets:

from pyknotid.make import trefoil
Traceback (most recent call last):
File "", line 1, in
File "/usr/local/lib/python3.10/site-packages/pyknotid/make/init.py", line 13, in
from pyknotid.make.torus import torus_knot, torus_link
File "/usr/local/lib/python3.10/site-packages/pyknotid/make/torus.py", line 14, in
from fractions import gcd
ImportError: cannot import name 'gcd' from 'fractions' (/usr/local/Cellar/python@3.10/3.10.0_2/Frameworks/Python.framework/Versions/3.10/lib/python3.10/fractions.py)

it seems that the problem is that this function has been replaced by math.gcd in python 3.9 and up:

https://docs.python.org/3/library/fractions.html