Require python3.9+

[stevobailey]

ieee754/ieee754/IEEE754.py

Line 200 in f193095

def hex(self) -> (str, list[str]):

Using list[str] as a return type requires python3.9 or greater. But I was able to install this on python3.6.

[canbula]

Thanks, you are right. The annotation list[str] is not really necessary for the functionality of the code. I will remove this part to ensure the compatibility with the older versions.

[canbula]

Solved with v0.11