Merge pull request #6124 from backstage/rugvip/noroutes

plugins,dev-utils: remove usage of deprecated route registrations

plugins/welcome/dev/index.tsx

@@ -14,7 +14,14 @@
  * limitations under the License.
  */
 
+import React from 'react';
 import { createDevApp } from '@backstage/dev-utils';
-import { welcomePlugin } from '../src/plugin';
+import { welcomePlugin, WelcomePage } from '../src/plugin';
 
-createDevApp().registerPlugin(welcomePlugin).render();
+createDevApp()
+  .registerPlugin(welcomePlugin)
+  .addPage({
+    title: 'Welcome',
+    element: <WelcomePage />,
+  })
+  .render();