support/testing: fix package/test_s6_networking.py

This test fails with the following error

  -sh: s6-tcpserver4: not found

In release 2.6.0.0 of s6-networking the `s6-tcpserver4` was unified into
a new `s6-tcpserver` command[1].

[1] https://github.com/skarnet/s6-networking/blob/master/NEWS#L33

Signed-off-by: Brandon Maier <brandon.maier@collins.com>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

support/testing/tests/package/test_s6_networking.py

@@ -28,7 +28,7 @@ class TestS6Networking(infra.basetest.BRTest):
         self.assertEqual(output[1][0:5], "after")
 
         # Test the TCP server and client
-        _, exit_code = self.emulator.run("s6-tcpserver4 127.0.0.1 1024 cat &")
+        _, exit_code = self.emulator.run("s6-tcpserver 127.0.0.1 1024 cat &")
         self.emulator.run("sleep 2")
         cmd = "echo foobar | s6-tcpclient 127.0.0.1 1024 s6-ioconnect -67"
         output, exit_code = self.emulator.run(cmd)