Bump portpicker from 1.5.2 to 1.6.0 (#89)

Bumps [portpicker](https://github.com/google/python_portpicker) from 1.5.2 to 1.6.0.
- [Changelog](https://github.com/google/python_portpicker/blob/main/ChangeLog.md)
- [Commits](google/python_portpicker@v1.5.2...v1.6.0)

---
updated-dependencies:
- dependency-name: portpicker
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements-test.txt

@@ -28,7 +28,7 @@ packaging==21.3
     # via pytest
 pluggy==1.0.0
     # via pytest
-portpicker==1.5.2
+portpicker==1.6.0
     # via -r requirements-test.in
 psutil==5.9.0
     # via portpicker