Bump psutil from 5.6.1 to 5.6.6

Bumps [psutil](https://github.com/giampaolo/psutil) from 5.6.1 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-5.6.1...release-5.6.6)

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

Author: dependabot[bot]

requirements.txt

@@ -52,7 +52,7 @@ pickleshare==0.7.5
 pluggy==0.8.0
 prometheus-client==0.6.0
 prompt-toolkit==1.0.14
-psutil==5.6.1
+psutil==5.6.6
 ptyprocess==0.6.0
 pycodestyle==2.4.0
 pydocstyle==3.0.0