ui: fixed launching the UI on more environments

Better resolve where the UI python package is.

related #59

ui/bin/opensnitch-ui

@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!/usr/bin/env python3
 
 from PyQt5 import QtWidgets, QtGui, QtCore
 
@@ -40,7 +40,7 @@ if __name__ == '__main__':
     parser.add_argument("--max-clients", dest="serverWorkers", default=10, help="Max number of allowed clients (incoming connections).")
 
     args = parser.parse_args()
-    
+
     os.environ["QT_AUTO_SCREEN_SCALE_FACTOR"] = "1"
     if supported_qt_version(5,6,0):
         try:
@@ -56,7 +56,7 @@ if __name__ == '__main__':
     server = grpc.server(futures.ThreadPoolExecutor(max_workers=int(args.serverWorkers)))
 
     add_UIServicer_to_server(service, server)
-    
+
     if args.socket.startswith("unix://"):
         socket = args.socket[7:]
         socket = os.path.abspath(socket)