Bump py from 1.8.1 to 1.9.0

Bumps [py](https://github.com/pytest-dev/py) from 1.8.1 to 1.9.0.
- [Release notes](https://github.com/pytest-dev/py/releases)
- [Changelog](https://github.com/pytest-dev/py/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/py@1.8.1...1.9.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

build/test-requirements.txt

@@ -18,6 +18,6 @@ isort
 
 # Python 2.7 support.
 pytest==4.6.9 ; python_version == '2.7'
-py==1.8.1 ; python_version == '2.7'  # via pytest 4
+py==1.9.0 ; python_version == '2.7'  # via pytest 4
 pathlib2>=2.2.0 ; python_version == '2.7'  # via pytest 4
 prospector==1.2.0 ; python_version == '2.7'