Bump pytest from 5.1.0 to 5.1.1

Bumps [pytest](https://github.com/pytest-dev/pytest) from 5.1.0 to 5.1.1.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@5.1.0...5.1.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements-test.txt

@@ -2,7 +2,7 @@
 pip>=9  # minimum installation requirements
 setuptools>=21  # minimum installation requirements
 coverage==4.5.4 # pytest-cov
-pytest==5.1.0
+pytest==5.1.1
 psycopg2-binary==2.8.3; platform_python_implementation != "PyPy"
 psycopg2cffi==2.8.1; platform_python_implementation == "PyPy"
 port-for==0.4