Need to update quantecon version in pyproject.toml

[gabriellequeran]

The previous version of quantecon used the function gcd(a, b) from fractions but since python 3.5 this function has been deprecated and since python 3.9, it has been moved to math.

[jstac]

Thanks @gabriellequeran , much appreciated. @Smit-create , if you have time, could you take a look at this please?

[Smit-create]

This issue is fixed by https://github.com/QuantEcon/QuantEcon.py/pull/573, and @mmcky is working on the build system in #608. Probably, after that, we won't require setup.py.

[mmcky]

thanks @Smit-create -- @gabriellequeran thanks for reporting I will try and organise a new release 0.5.3 tomorrow with the fixes.

[mmcky]

Actually @gabriellequeran this is already in 0.5.2 so perhaps you can try:

pip install quantecon --upgrade

and see if you still have this issue.