proxy-backend: allow unauthenticated requests

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/five-grapes-love.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-proxy-backend': patch
+---
+
+Allow unauthenticated requests.

plugins/proxy-backend/src/alpha.ts

@@ -44,6 +44,10 @@ export default createBackendPlugin({
             logger: loggerToWinstonLogger(logger),
           }),
         );
+        httpRouter.addAuthPolicy({
+          allow: 'unauthenticated',
+          path: '/',
+        });
       },
     });
   },