prepare for oauth

lib/i18n/en_US.json

@@ -1,5 +1,5 @@
 {
-    "greeting": "Hello!", 
+    "greeting": "hello!", 
     "user-id-not-valid": "Sorry, this user id doesn't look quite right... ",
     "user-id": "user id",
     "user-id-example": "user@example.com",

lib/pages/login.dart

@@ -60,7 +60,7 @@ class _LoginFormState extends State<LoginForm> {
           ),
           TextButton.icon(
               onPressed: () {
-                final isValid = formKey.currentState!.validate();
+                formKey.currentState!.validate();
               },
               icon: const Icon(Icons.login),
               label: Text("authorize-in-browser".i18n()))