Remove typing dependency

[thoger-rh]

The typing project is archived on pypi, as typing module is part of the Python standard library as of version 3.5.

Requiring typing when using Python 3.5 and later is not needed.

Reference: https://pypi.org/project/typing/

[thoger-rh]

They typing project description on pypi also notes that using typing;python_version<"3.5" might be an alternative. While this works with current Python / pip versions, I got this error when trying to use that with Python 3.4 + pip version form that era:

'install_requires' must be a string or list of strings containing valid project/version requirement specifiers

Python 3.5.0 was released in Sep 2015, 10+ years ago.