Modified TestProxyPROXYOut to conform with the fixed version of PROXY protocol header format

original code sent the header in the format: PROXY <family> <srcIP>
<srcPort> <dstIP> <dstPort>
according to docs header format should be:
PROXY <family> <srcIP> <dstIP> <srcPort> <dstPort>

this is according
to:
https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt
section
2.1. Human-readable header format (Version 1).

Author: AdamEr8

tcpproxy_test.go

@@ -320,7 +320,7 @@ func TestProxyPROXYOut(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	want := fmt.Sprintf("PROXY TCP4 %s %d %s %d\r\nfoo", toFront.LocalAddr().(*net.TCPAddr).IP, toFront.LocalAddr().(*net.TCPAddr).Port, toFront.RemoteAddr().(*net.TCPAddr).IP, toFront.RemoteAddr().(*net.TCPAddr).Port)
+	want := fmt.Sprintf("PROXY TCP4 %s %s %d %d\r\nfoo", toFront.LocalAddr().(*net.TCPAddr).IP, toFront.RemoteAddr().(*net.TCPAddr).IP, toFront.LocalAddr().(*net.TCPAddr).Port, toFront.RemoteAddr().(*net.TCPAddr).Port)
 	if string(bs) != want {
 		t.Fatalf("got %q; want %q", bs, want)
 	}