Update py to 1.8.0

[pyup-bot]

This PR updates py from 1.7.0 to 1.8.0.

Changelog

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.

Links

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

[codecov]

Codecov Report

Merging #403 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #403   +/-   ##
=======================================
  Coverage   98.57%   98.57%           
=======================================
  Files           8        8           
  Lines         702      702           
  Branches      125      125           
=======================================
  Hits          692      692           
  Misses          2        2           
  Partials        8        8

---

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[codecov]

Codecov Report

Merging #403 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #403   +/-   ##
=======================================
  Coverage   98.57%   98.57%           
=======================================
  Files           8        8           
  Lines         702      702           
  Branches      125      125           
=======================================
  Hits          692      692           
  Misses          2        2           
  Partials        8        8

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 52b7d72...05cf20e. Read the comment docs.

[codecov]

Codecov Report

Merging #403 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #403   +/-   ##
=======================================
  Coverage   98.57%   98.57%           
=======================================
  Files           8        8           
  Lines         702      702           
  Branches      125      125           
=======================================
  Hits          692      692           
  Misses          2        2           
  Partials        8        8

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 52b7d72...05cf20e. Read the comment docs.