[googleapis_auth] prepare beta release

[kevmoo]

No description provided.

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:_discoveryapis_commons	1.0.8-wip	WIP (no publish necessary)
package:discoveryapis_generator	1.1.0-wip	WIP (no publish necessary)
package:googleapis	16.0.0	already published at pub.dev
package:googleapis_auth	2.1.0-beta.1	ready to publish	googleapis_auth-v2.1.0-beta.1
package:googleapis_beta	9.1.0-wip	WIP (no publish necessary)

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.

[github-actions]

PR Health

License Headers ✔️

// Copyright (c) 2026, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

Files
no missing headers

All source files should start with a license header.

This check can be disabled by tagging the PR with skip-license-check.

API leaks ✔️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbol	Leaking sources

This check can be disabled by tagging the PR with skip-leaking-check.

Breaking changes ✔️

Package	Change	Current Version	New Version	Needed Version	Looking good?
googleapis_auth	Breaking	2.0.0	2.1.0-beta.1	2.1.0-beta.1	✔️

This check can be disabled by tagging the PR with skip-breaking-check.

Unused Dependencies ✔️

Package	Status
googleapis_auth	✔️ All dependencies utilized correctly.

For details on how to fix these, see dependency_validator.

This check can be disabled by tagging the PR with skip-unused-dependencies-check.

Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

This check can be disabled by tagging the PR with skip-changelog-check.