Update py to 1.5.1

[pyup-bot]

There's a new version of py available.
You are currently using 1.4.34. I have updated it to 1.5.1

These links might come in handy: PyPI | Changelog | Repo | Docs

Changelog

1.5.1

=====

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

1.5.0

=====

• 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.

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖

[pyup-bot]

Closing this in favor of #153