The project requires a very simple tox file and so can remove a lot of
boilerplate and re-specifying of tox defaults. When using py36 notation,
the "basepython" configuration option has a correct default.

Python 2.6 and 3.3 are end of life. They are no longer receiving bug
fixes, including for security issues. Python 2.6 went EOL on 2013-10-29
and 3.3 on 2017-09-29. For additional details on supported Python
versions, see:

https://devguide.python.org/#status-of-python-branches

Removing support for EOL Pythons will reduce testing and maintenance
resources.

Using pypinfo, here are the download statistics for Unidecode over the
last 30 days, showing minimal 3.3 & 2.6 installs.

$ pypinfo --percent unidecode pyversion

| python_version | percent | download_count |
| -------------- | ------- | -------------- |
| 2.7            |  66.07% |        244,263 |
| 3.6            |  19.69% |         72,777 |
| 3.5            |   8.27% |         30,585 |
| 3.4            |   5.59% |         20,663 |
| 3.7            |   0.29% |          1,062 |
| 2.6            |   0.06% |            210 |
| 3.8            |   0.02% |             72 |
| 3.3            |   0.01% |             44 |
| 3.2            |   0.00% |              6 |
| None           |   0.00% |              2 |

These codepoints are defined as "Greek small letter mu" and a Latin capital
letter, not with spelled-out unit names.

"u" is a common way of representing "micro" SI prefix in ASCII.