add core styles to create-react-app tests

test/endtoend/create-react-app/src/App.js

@@ -4,6 +4,7 @@ import Tus from '@uppy/tus'
 import GoogleDrive from '@uppy/google-drive'
 import { Dashboard, DashboardModal } from '@uppy/react'
 // import { Dashboard, DashboardModal, DragDrop, ProgressBar } from '@uppy/react'
+import '@uppy/core/dist/style.css'
 import '@uppy/dashboard/dist/style.css'
 // import '@uppy/drag-drop/dist/style.css'
 // import '@uppy/progress-bar/dist/style.css'