Python Project Guide in project-team-guide fix dead link

[alan hoang]

This link is died.
oslo_debug_helper
Should be update with `https://docs.openstack.org/oslotest/latest/user/features.html`

This bug tracker is for errors with the documentation, use the following as a template and remove or add fields as you see fit. Convert [ ] into [x] to check boxes:

- [ ] This doc is inaccurate in this way: ______
- [ ] This is a doc addition request.
- [ ] I have a fix to the document that I can paste below including example: input and output.

If you have a troubleshooting or support issue, use the following resources:

 - Ask OpenStack: http://ask.openstack.org
 - The mailing list: http://lists.openstack.org
 - IRC: 'openstack' channel on Freenode

-----------------------------------
Release: 0.0.1.dev153 on 2017-12-12 13:36
SHA: 374ade6026a9a0e7dcf78346e8ed18e4a9b49e34
Source: https://git.openstack.org/cgit/openstack/project-team-guide/tree/doc/source/project-setup/python.rst
URL: https://docs.openstack.org/project-team-guide/project-setup/python.html

[Andreas Jaeger (jaegerandi)]

Fix:
 https://review.openstack.org/546899