Change react-testing-library to @testing-library/react

Relevant issue: testing-library/dom-testing-library#260

Author: kaykayehnn

src/templates/component/test.hbs

@@ -1,5 +1,5 @@
 import React from 'react'
-import { render } from 'react-testing-library'
+import { render } from '@testing-library/react'
 
 import {{name}} from '.'
 

src/templates/container/test.hbs

@@ -1,5 +1,5 @@
 import React from 'react'
-import { render } from 'react-testing-library'
+import { render } from '@testing-library/react'
 
 import {{name}} from '.'