add missing connect call

Author: anandkumarpatel

samples/tutorials/node.js/macOS/SqlServerColumnstoreSample/columnstore.js

@@ -44,4 +44,7 @@ connection.on('connect', function(err) {
             exec('SELECT SUM(Price) FROM Table_with_5M_rows');
         },
     ]);
-});
+});
+
+// Initialize the connection.
+connection.connect();