CI: Bump flake8 and hacking to make pep8 happy

Signed-off-by: George Melikov <mail@gmelikov.ru>

Author: gmelikov

test-requirements.txt

@@ -1,6 +1,7 @@
-hacking>=0.12.0,!=0.13.0,<0.14 # Apache-2.0
+hacking<3  # Apache-2.0
 typing-extensions<4.2.0;python_version=='3.6'  # PSF-2.0
 pytest-timer
 pytest==4.6.1
 coverage>=4.0 # Apache-2.0
 mock==3.0.5
+flake8>=3.8.4  # Flake8 License (MIT)