[tests] Increase test timeout from 60 seconds to 180 seconds

We see SimpleActorTest timing out a lot in our CI, and from the logs
it appears likely that this is a valid timeout (versus the test just
being stuck). Let us increase the test timeout and see if it helps.

tests/meson.build

@@ -98,7 +98,7 @@ foreach source, test_dict : tests
 	   test_exe,
 	   is_parallel: test_dict.get('is_parallel', false),
 	   suite: test_dict.get('test_suite', 'all'),
-	   timeout: 60,
+	   timeout: 180,
 	   env: test_env,
 	  )
 endforeach