Fix notification passing for Actor MCP servers

[MQ37]

When you call a tool from MCP server deployed on Apify as an standby Actor (Actorized MCP server) it does not pass the notifications to the client even through there is a handler registered for that - for some reason even the handler does not receive the notification.

Related to #151

For context src/mcp/server.ts:

                        // TODO: for some reason the client does not receive notifications
                        // we need to investigate this
                        // Set up notification handlers for the client
                        for (const schema of ServerNotificationSchema.options) {
                            const method = schema.shape.method.value;
                            // Forward notifications from the proxy client to the server
                            client.setNotificationHandler(schema, async (notification) => {
                                log.info('Sending MCP notification', {
                                    method,
                                    notification,
                                });
                                await extra.sendNotification(notification);
                            });
                        }