Bump psutil from 5.6.2 to 5.6.6

Bumps [psutil](https://github.com/giampaolo/psutil) from 5.6.2 to 5.6.6.
- [Release notes](https://github.com/giampaolo/psutil/releases)
- [Changelog](https://github.com/giampaolo/psutil/blob/master/HISTORY.rst)
- [Commits](giampaolo/psutil@release-5.6.2...release-5.6.6)

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

Author: dependabot[bot]

setup.py

@@ -17,7 +17,7 @@
         'hypothesis==3.82',
         'attrs==19.1.0',
         'enum34==1.1.6',
-        'psutil==5.6.2'
+        'psutil==5.6.6'
     ],
     tests_requires=[
         'pytest==4.5.0',