Remove support for Python 3.4
Python 3.4 has been end-of-life'd as-of March 18th 2019.
DEPRECATION: Python 3.4 support has been deprecated. pip 19.1 will be the last one supporting it. Please upgrade your Python as Python 3.4 won't be maintained after March 2019 (cf PEP 429).
Maybe once Python 3.5.8 has been released in September 2019, removing 3.4 as a supported version will make sense.