[deps] Update nose2 requirement from >=0.6.5 to >=0.16.0

Updates the requirements on [nose2](https://github.com/nose-devs/nose2) to permit the latest version.
- [Changelog](https://github.com/nose-devs/nose2/blob/main/docs/changelog.rst)
- [Commits](nose-devs/nose2@0.6.5...0.16.0)

---
updated-dependencies:
- dependency-name: nose2
  dependency-version: 0.16.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements-test.txt

@@ -1,4 +1,4 @@
-nose2[coverage_plugin]>=0.6.5
+nose2[coverage_plugin]>=0.16.0
 responses~=0.25.8
 openwisp-utils[qa]~=1.2.2
 parameterized~=0.9.0