Update py to 1.8.1

[pyup-bot]

This PR updates py from 1.4.34 to 1.8.1.

Changelog

1.8.1

==================

- Handle ``FileNotFoundError`` when trying to import pathlib in ``path.common``
on Python 3.4 (207).

- ``py.path.local.samefile`` now works correctly in Python 3 on Windows when dealing with symlinks.

1.8.0

==================

- add ``"importlib"`` pyimport mode for python3.5+, allowing unimportable test suites
to contain identically named modules.

- fix ``LocalPath.as_cwd()`` not calling ``os.chdir()`` with ``None``, when
being invoked from a non-existing directory.

1.7.0

==================

- fix 174: use ``shutil.get_terminal_size()`` in Python 3.3+ to determine the size of the
terminal, which produces more accurate results than the previous method.

- fix pytest-dev/pytest2042: introduce new ``PY_IGNORE_IMPORTMISMATCH`` environment variable
that suppresses ``ImportMismatchError`` exceptions when set to ``1``.

1.6.0

==================

- add ``TerminalWriter.width_of_current_line`` (i18n version of
``TerminalWriter.chars_on_current_line``), a read-only property
that tracks how wide the current line is, attempting to take
into account international characters in the calculation.

1.5.4

==================

- fix pytest-dev/pytest3451: don't make assumptions about fs case sensitivity
in ``make_numbered_dir``.

1.5.3

=====

- fix 179: ensure we can support 'from py.error import ...'

1.5.2

=====

- fix 169, 170: error importing py.log on Windows: no module named ``syslog``.

1.5.1

=====

- fix 167 - prevent pip from installing py in unsupported Python versions.

1.5.0

=====

NOTE: **this release has been removed from PyPI** due to missing package
metadata which caused a number of problems to py26 and py33 users.
This issue was fixed in the 1.5.1 release.

- python 2.6 and 3.3 are no longer supported
- deprecate py.std and remove all internal uses
- fix 73 turn py.error into an actual module
- path join to / no longer produces leading double slashes
- fix 82 - remove unsupportable aliases
- fix python37 compatibility of path.sysfind on windows by correctly replacing vars
- turn iniconfig and apipkg into vendored packages and ease de-vendoring for distributions
- fix 68 remove invalid py.test.ensuretemp references
- fix 25 - deprecate path.listdir(sort=callable)
- add ``TerminalWriter.chars_on_current_line`` read-only property that tracks how many characters
have been written to the current line.

Links

• PyPI: https://pypi.org/project/py
• Changelog: https://pyup.io/changelogs/py/
• Docs: http://py.readthedocs.io/

[pyup-bot]

Closing this in favor of #135