Use PBR's setup.py test command

There is setup.py test provided by pbr and there is setup.py testr
provided by testr. The `test` command is still supported by PBR and is a
semi standard way of doing things whereas `testr` in upstream testr is
not really supported by them. Therefore use `test`.

Change-Id: I77f37fd2287204e8f1e7f5a96f47453eb10e720d
1 file changed