Update pytest-salt url

Updates pytest-salt url to point to
https://github.com/vmware-archive/pytest-salt. Should re-work tests
to use pytest-salt-factories.

tests/requirements.txt

@@ -2,7 +2,7 @@ mock
 pytest>=3.5.0,<4.0.0
 pytest-rerunfailures
 pytest-cov
-git+https://github.com/saltstack/pytest-salt@master#egg=pytest-salt
+git+https://github.com/vmware-archive/pytest-salt@master#egg=pytest-salt
 tornado<5.0.0
 CherryPy
 setuptools_scm