The `pkg_resources` package inside `setuptools` explicitly [disallows
Python 3.3](7392f01ffc (diff-81de4a30a55fcc3fb944f8387ea9ec94)):
if (3, 0) < sys.version_info < (3, 4):
raise RuntimeError("Python 3.4 or later is required")
It's time to drop support for 3.3.
Because installing dependencies for `coveralls` now fails with:
Collecting pycparser (from cffi>=1.7->cryptography>=1.3.4; python_version <= "2.7" and extra == "secure"->urllib3[secure]; python_version < "3"->coveralls)
[...]
pycparser requires Python '>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*' but the running Python is 2.6.9
Use the `--strict` flag to check all rules on local YAML files, to
prevent all problems (including warnings). This includes the newly added
`truthy` rule.
