Drop support for EOL Python 3.4

[hugovk]

Python 3.4 is EOL since 2019-03-16 and no longer receiving security updates (or any updates) from the core Python team.

Source: https://en.wikipedia.org/wiki/CPython#Version_history

It's also little used.

Here's the pip installs for pyscreenshot from PyPI for April 2019:

category	percent	downloads
2.7	69.20%	27,363
3.6	14.05%	5,557
3.7	13.93%	5,509
3.5	1.77%	698
null	0.79%	312
3.4	0.26%	101
3.8	0.01%	3
Total		39,543

Source: pypistats python_minor pyscreenshot --last-month # pip install pypistats

[ponty]

Thanks