Bump google-github-actions/auth from 2.1.4 to 2.1.5 (#1406)

Bumps [google-github-actions/auth](https://github.com/google-github-actions/auth) from 2.1.4 to 2.1.5.
- [Release notes](https://github.com/google-github-actions/auth/releases)
- [Changelog](https://github.com/google-github-actions/auth/blob/main/CHANGELOG.md)
- [Commits](google-github-actions/auth@v2.1.4...v2.1.5)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Antoine Toulme <atoulme@splunk.com>

.github/workflows/functional_test_v2.yaml

@@ -221,7 +221,7 @@ jobs:
             ~/go/bin
             ~/go/pkg/mod
           key: go-cache-${{ runner.os }}-${{ hashFiles('**/go.sum') }}
-      - uses: 'google-github-actions/auth@v2.1.4'
+      - uses: 'google-github-actions/auth@v2.1.5'
         with:
           project_id: ${{ secrets.GKE_PROJECT }}
           credentials_json: ${{ secrets.GKE_SA_KEY }}
@@ -284,7 +284,7 @@ jobs:
             ~/go/bin
             ~/go/pkg/mod
           key: go-cache-${{ runner.os }}-${{ hashFiles('**/go.sum') }}
-      - uses: 'google-github-actions/auth@v2.1.4'
+      - uses: 'google-github-actions/auth@v2.1.5'
         with:
           project_id: ${{ secrets.GKE_PROJECT }}
           credentials_json: ${{ secrets.GKE_SA_KEY }}