fix(shorebird_cli): update 'SHOREBIRD_TOKEN needs refresh' warning (#1768)

packages/shorebird_cli/integration_test/shorebird_cli_integration_test.dart

@@ -16,9 +16,8 @@ import 'package:test/test.dart';
 import 'package:uuid/uuid.dart';
 
 const tokenWarningMessage = '''
-[WARN] The value of SHOREBIRD_TOKEN is not a valid base64-encoded token. This
-will become an error in the next major release. Run `shorebird login:ci` before
-then to obtain a new token.
+[WARN] $shorebirdTokenEnvVar needs to be updated before the next major release.
+Run `shorebird login:ci` to obtain a new token.
 ''';
 
 R runWithOverrides<R>(R Function() body) {

packages/shorebird_cli/lib/src/auth/auth.dart

@@ -271,9 +271,8 @@ class Auth {
         // TODO(bryanoltman): Remove this legacy behavior after July 2024 or
         // next major release.
         logger.warn('''
-The value of $shorebirdTokenEnvVar is not a valid base64-encoded token. This
-will become an error in the next major release. Run `shorebird login:ci` before
-then to obtain a new token.''');
+[WARN] $shorebirdTokenEnvVar needs to be updated before the next major release.
+Run `shorebird login:ci` to obtain a new token.''');
         _token = CiToken(
           refreshToken: envToken,
           authProvider: AuthProvider.google,

packages/shorebird_cli/test/src/auth/auth_test.dart

@@ -423,9 +423,8 @@ void main() {
           auth = buildAuth();
           verify(
             () => logger.warn('''
-The value of $shorebirdTokenEnvVar is not a valid base64-encoded token. This
-will become an error in the next major release. Run `shorebird login:ci` before
-then to obtain a new token.'''),
+[WARN] SHOREBIRD_TOKEN needs to be updated before the next major release.
+Run `shorebird login:ci` to obtain a new token.'''),
           ).called(1);
         });
       });