chore(deps): bump sigstore/cosign-installer from 3.8.1 to 3.9.1

Bumps [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) from 3.8.1 to 3.9.1.
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](sigstore/cosign-installer@d7d6bc7...398d4b0)

---
updated-dependencies:
- dependency-name: sigstore/cosign-installer
  dependency-version: 3.9.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

.github/workflows/build-verify.yml

@@ -54,7 +54,7 @@ jobs:
 
       - name: Install Cosign
         if: github.repository_owner == 'microcks' && env.PACKAGE_IMAGE == 'true'
-        uses: sigstore/cosign-installer@d7d6bc7722e3daa8354c50bcb52f4837da5e9b6a # v3.8.1
+        uses: sigstore/cosign-installer@398d4b0eeef1380460a10c8013a76f728fb906ac # v3.9.1
 
       - name: Set up QEMU
         if: github.repository_owner == 'microcks' && env.PACKAGE_IMAGE == 'true'