Set daemon attribute instead of using setDaemon method that was deprecated in Python 3.10

Author: tirkarthi

git/cmd.py

@@ -103,7 +103,7 @@ def pump_stream(cmdline, name, stream, is_decode, handler):
     for name, stream, handler in pumps:
         t = threading.Thread(target=pump_stream,
                              args=(cmdline, name, stream, decode_streams, handler))
-        t.setDaemon(True)
+        t.daemon = True
         t.start()
         threads.append(t)