Fix test on hapi 18

Author: hueniverse

test/manager.js

@@ -311,7 +311,7 @@ describe('Manager', () => {
         server.route({ method: 'GET', path: '/', handler: { view: { template: 'test.html' } } });
 
         const res = await server.inject('/');
-        expect(res.statusCode).to.equal(204);
+        expect(res.statusCode).to.be.within(200, 204);
     });
 
     it('allows the context to be modified by extensions', async () => {