Determine windows version reliably

Fixes #9578

gajim/common/zeroconf/client_zeroconf.py

@@ -16,7 +16,6 @@
 # along with Gajim.  If not, see <http://www.gnu.org/licenses/>.
 
 import socket
-import platform
 import ssl
 import errno
 import sys
@@ -76,7 +75,7 @@ class ZeroconfListener(IdleObject):
         self._serv.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
         self._serv.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
         if os.name == 'nt':
-            if int(platform.win32_ver()[0]) >= 6:  # Win Vista +
+            if sys.getwindowsversion().major >= 6:  # Win Vista +
                 # 47 is socket.IPPROTO_IPV6
                 # 27 is socket.IPV6_V6ONLY under windows, but not defined ...
                 self._serv.setsockopt(41, 27, 0)