Bump pytest from 4.6.3 to 5.3.5

Bumps [pytest](https://github.com/pytest-dev/pytest) from 4.6.3 to 5.3.5.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@4.6.3...5.3.5)

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

Author: dependabot-preview[bot]

requirements.txt

@@ -1,7 +1,7 @@
 boto3==1.11.5
 empyrical==0.5.0
 pyre-check==0.0.39
-pytest==4.6.3
+pytest==5.3.5
 pyti==0.2.2
 safety==1.8.5
 sklearn==0.0
@@ -11,7 +11,7 @@ tabulate==0.8.3
 tox==3.13.2
 pylint==2.3.1
 pyre-check==0.0.39
-pytest==4.6.3
+pytest==5.3.5
 pyti==0.2.2
 safety==1.8.5
 yapf==0.27.0