plugins/auth-backend: read backend.baseUrl from config

packages/backend/src/plugins/auth.ts

@@ -17,6 +17,9 @@
 import { createRouter } from '@backstage/plugin-auth-backend';
 import { PluginEnvironment } from '../types';
 
-export default async function createPlugin({ logger }: PluginEnvironment) {
-  return await createRouter({ logger });
+export default async function createPlugin({
+  logger,
+  config,
+}: PluginEnvironment) {
+  return await createRouter({ logger, config });
 }