fix: Allow Playground to work in Serverless mode

Author: paveltiunov

packages/cubejs-playground/package.json

@@ -52,6 +52,7 @@
     "public",
     "build"
   ],
+  "homepage": ".",
   "proxy": "http://localhost:4000",
   "license": "MIT",
   "devDependencies": {

packages/cubejs-playground/src/index.js

@@ -9,7 +9,7 @@ import DashboardPage from './DashboardPage';
 import App from './App';
 import { page } from './events';
 
-const history = createHashHistory({ basename: process.env.PUBLIC_URL });
+const history = createHashHistory();
 history.listen((location) => {
   page(location);
 });