build(deps): bump google-github-actions/auth in the gha group

Bumps the gha group with 1 update: [google-github-actions/auth](https:/google-github-actions/auth).


Updates `google-github-actions/auth` from 2.1.5 to 2.1.6
- [Release notes](https:/google-github-actions/auth/releases)
- [Changelog](https:/google-github-actions/auth/blob/main/CHANGELOG.md)
- [Commits](google-github-actions/auth@v2.1.5...v2.1.6)

---
updated-dependencies:
- dependency-name: google-github-actions/auth
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: gha
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/build.yaml

@@ -111,7 +111,7 @@ jobs:
  steps:
  - id: "auth"
  name: "Authenticate to Google Cloud"
- uses: "google-github-actions/[email protected].5"
+ uses: "google-github-actions/[email protected].6"
  with:
  workload_identity_provider: ${{ secrets.NAIS_IO_WORKLOAD_IDENTITY_PROVIDER }}
  service_account: "[email protected]"