Python 2.7 and 3.4 are end-of-life. They are no longer receiving bug
fixes, including for security issues. Python 2.7 went EOL on 2020-01-01
and 3.4 on 2019-03-18. For additional details on support Python
versions, see:

Supported: https://devguide.python.org/#status-of-python-branches
EOL: https://devguide.python.org/devcycle/#end-of-life-branches

Removing support for EOL Pythons will reduce testing and maintenance
resources while allowing the library to move towards modern Python 3.

Using pypinfo, we can show the PyPI download statistics, showing less
than 10% of users are using Python 2.7.

| python_version | percent | download_count |
| -------------- | ------: | -------------: |
| 3.7            |  45.36% |      3,056,010 |
| 3.6            |  26.46% |      1,782,778 |
| 3.8            |  12.22% |        823,213 |
| 2.7            |   9.97% |        671,459 |
| 3.5            |   5.86% |        394,846 |
| 3.4            |   0.10% |          6,700 |
| 3.9            |   0.03% |          2,346 |
| 2.6            |   0.00% |             57 |
| 3.3            |   0.00% |             21 |
| 3.10           |   0.00% |              6 |
| Total          |         |      6,737,436 |

Library users who continue to use Python 2.7 will still be able to
install previous versions of sqlparse.

Compatibility shims have been dropped, simplifying the code.

Using pyupgrade, the codebase has been updated to take advantage of
modern syntax <https://github.com/asottile/pyupgrade>.

The wheel is no longer marked as "universal" as it is now Python 3 only.

        if (self.stmtprocess or self.postprocess or
                self.split_statements or self._grouping):
always evaluates to true after removing unused features