Bump pytest from 5.4.3 to 6.1.2 (#233)

Bumps [pytest](https://github.com/pytest-dev/pytest) from 5.4.3 to 6.1.2.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@5.4.3...6.1.2)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

requirements.txt

@@ -5,7 +5,7 @@ pytest-cov==2.10.1
 pytest-tornasync==0.6.0.post2; python_version >= '3.5'
 pytest-trio==0.6.0; python_version>="3.6"
 pytest==4.6.6; python_version<"3.5"
-pytest==5.4.3; python_version>="3.5"
+pytest==6.1.2; python_version>="3.5"
 six==1.15.0
 tornado==5.1.1; python_version<"3.6"
 tornado==6.0.4; python_version>="3.6"