python3: Fix tox requirements
python3: Fix tox requirements

Update tox.ini to no to install distribute. Also bump
testrepository to a newerver version since it fixes some
python3 compat issues.

Change-Id: I735dc28cdb94e3376b391d11220c1ba90ddb8b2e
Signed-off-by: Chuck Short <753a8074f04ffd62a8fff7516e3ae689be8e35ad@canonical.com>

ntt-sic/python-cinderclient,ntt-sic/python-cinderclient,swamireddy/python-cinderclient,JioCloud/python-cinderclient,varunarya10/python-cinderclient,citrix-openstack-build/python-cinderclient,metacloud/python-cinderclient,citrix-openstack-build/python-cinderclient,eayunstack/python-cinderclient,scottdangelo/cinderclient-api-microversions,metacloud/python-cinderclient,varunarya10/python-cinderclient,JioCloud/python-cinderclient,eayunstack/python-cinderclient,swamireddy/python-cinderclient,scottdangelo/cinderclient-api-microversions