Python version on pypi is 3.5, while in fact Python 3.6 is needed

On pypi (https://pypi.org/project/pyphysio/) pyphysio is classified under Python's 3.5 version, while there are f-String expressions in the code, and these were introduced in Python 3.6, see: https://www.python.org/dev/peps/pep-0498/ and https://realpython.com/python-f-strings/

Other than that minor installation issue it is a great module, thank you!