Bump sigstore/cosign-installer from 3.8.2 to 3.9.1 (#7)

Bumps [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) from 3.8.2 to 3.9.1.
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](sigstore/cosign-installer@3454372...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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/release.yml

@@ -71,7 +71,7 @@ jobs:
             ./cmd/server
 
       - name: Install Cosign
-        uses: sigstore/cosign-installer@3454372f43399081ed03b604cb2d021dabca52bb # v3.8.2
+        uses: sigstore/cosign-installer@398d4b0eeef1380460a10c8013a76f728fb906ac # v3.9.1
 
       - name: Sign Image with Cosign
         env: