Bump configobj from 5.0.6 to 5.0.9 in /tests/python2-libraries

Bumps [configobj](https://github.com/DiffSK/configobj) from 5.0.6 to 5.0.9.
- [Release notes](https://github.com/DiffSK/configobj/releases)
- [Changelog](https://github.com/DiffSK/configobj/blob/release/CHANGES.rst)
- [Commits](DiffSK/configobj@v5.0.6...v5.0.9)

---
updated-dependencies:
- dependency-name: configobj
  dependency-type: direct:production
...

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

tests/python2-libraries/requirements.txt

@@ -27,7 +27,7 @@ click==6.7
 cliff==2.13.0
 cmd2==0.8.9
 colorama==0.3.9
-configobj==5.0.6
+configobj==5.0.9
 cov-core==1.15.0
 coverage==4.5.1
 coveralls==1.4.0