chore(deps): bump google-cloud-auth from 0.20.0 to 0.21.0

Bumps [google-cloud-auth](https://github.com/googleapis/google-cloud-rust) from 0.20.0 to 0.21.0.
- [Release notes](https://github.com/googleapis/google-cloud-rust/releases)
- [Commits](https://github.com/googleapis/google-cloud-rust/commits)

---
updated-dependencies:
- dependency-name: google-cloud-auth
  dependency-version: 0.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Cargo.lock

@@ -79,7 +79,7 @@ ed25519-dalek = "2.2"
 stellar-strkey = "0.0.13"
 soroban-rs = "0.2.5"
 p256 = { version = "0.13.2" }
-google-cloud-auth = "0.20.0"
+google-cloud-auth = "0.22.1"
 http = { version = "1.3.1" }
 pem = { version = "3" }
 simple_asn1 = { version = "0.6" }