Bump psutil from 5.2.2 to 5.6.6

Bumps [psutil](https://github.com/giampaolo/psutil) from 5.2.2 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-5.2.2...release-5.6.6)

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

requirements.txt

@@ -1,7 +1,7 @@
 bottle==0.12.13
 beaker==1.9.0
 pyyaml>=4.2b1
-psutil==5.2.2
+psutil==5.6.6
 pytoml==0.1.13
 docker-py==1.1.0
 boto==2.48.0