[vala/0.40] tests: Don't use deprecated syntax to connect signals

[Rico Tzschichholz <ricotz src gnome org>]

commit 00b4a491ef10f5131d51b39f9ee5ec14499c5969
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sun Sep 23 09:42:19 2018 +0200

    tests: Don't use deprecated syntax to connect signals

 tests/objects/properties.vala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/tests/objects/properties.vala b/tests/objects/properties.vala
index 9c06888c5..f34f97c66 100644
--- a/tests/objects/properties.vala
+++ b/tests/objects/properties.vala
@@ -41,10 +41,10 @@ public class Sample : Object {
        }
 
        public void run() {
-               notify += (s, p) => {
+               notify.connect ((s, p) => {
                        stdout.printf("property `%s' has changed!\n",
                                      p.name);
-               };
+               });
 
 
                automatic = "TheNewAutomatic";