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.

Both Python 2.7 and Python 3 have the type bytes. On Python 2.7, it is
an alias of str, same as was previously defined in compat.py. Makes the
code slightly more compatible with Python 3 style syntax. Observe:

    $ python2
    >>> bytes
    <type 'str'>

- If user provides an encoding value, use it instead of trying to _guess_ first.
- If no value is provided, then decode with default of utf-8, otherwise
  try with unicode-escape

Signed-off-by: Tao Wang <twang2218@gmail.com>

Raise TypeError if the input is neither bytes in a known encoding nor
unicode nor a file-like object (file, StringIO).

Remove function u(). Add bytes_type to compat. Add tests for non-ascii.

This reverts commit 2893bd1857d685cf892beac3a7429d03cf1a09f1.