fix(windows): use correct `salt-minion` package name

* From `salt-winrepo-ng`:
  + https://github.com/saltstack/salt-winrepo-ng/blob/master/salt-minion-py2.sls
    - Package: `salt-minion`
  + https://github.com/saltstack/salt-winrepo-ng/blob/master/salt-minion-py3.sls
    - Package: `salt-minion-py3`
* Close #411

salt/osfamilymap.yaml

   python_git: py-GitPython
 
 Windows:
-  salt_minion: salt-minion
+  salt_minion: salt-minion{{ py_ver_repr }}
   config_path: 'C:\salt\conf'
   minion_service: salt-minion
 

salt/ospyvermap.yaml

 
 OpenBSD: {}
 
+# This is *not* used directly with https://repo.saltstack.com
+# Rather, this is used with `salt-winrepo-ng`, where the package names are:
+# * py2: salt-minion
+# * py3: salt-minion-py3
 Windows:
-  py2: 'Py2'
-  py3: 'Py3'
+  py2: ''
+  py3: '-py3'
 
 MacOS:
   py2: 'py2'