feat: fixes #523. Remove the default export from plugins

plugins/welcome/src/index.ts

@@ -14,4 +14,4 @@
  * limitations under the License.
  */
 
-export { default } from './plugin';
+export { plugin } from './plugin';

plugins/welcome/src/plugin.ts

@@ -17,7 +17,7 @@
 import { createPlugin } from '@backstage/core';
 import WelcomePage from 'components/WelcomePage';
 
-export default createPlugin({
+export const plugin = createPlugin({
   id: 'welcome',
   register({ router, featureFlags }) {
     router.registerRoute('/', WelcomePage);