Bump pytest from 4.6.5 to 4.6.6

Bumps [pytest](https://github.com/pytest-dev/pytest) from 4.6.5 to 4.6.6.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@4.6.5...4.6.6)

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

requirements.txt

@@ -130,7 +130,7 @@ coverage==4.5.4
 parse-type==0.5.2
 poster~=0.8.1
 flake8==3.7.8
-pytest==4.6.5
+pytest==4.6.6
 pytest-bdd==3.2.1
 splinter==0.11.0
 pytest-splinter==2.0.1