Use python_requires='>=3.5'

[gopackgo90]

Issue description

This library should use python_requires to enforce the supported Python version with pip.

[hollabaq86]

👋 @gopackgo90 thanks for reaching out. I've marked this for the next-major-version since the notes on the docs you referenced mention that only versions 9.0.0 and higher of pip recognize the python_requires metadata.

It's my understanding that not everyone who develops in python uses pip, so I'm curious on the ramifications to folks using other dependency management frameworks would experience by our adding this enforcement.

[hollabaq86]

based on my conversations with pip maintainers, we should be safe to add this into the next major version.

for internal tracking, ticket 2056