Bump sigstore/cosign-installer

Bumps [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) from f713795cb21599bc4e5c4b58cbad1da852d7eeb9 to 398d4b0eeef1380460a10c8013a76f728fb906ac.
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](sigstore/cosign-installer@f713795...398d4b0)

---
updated-dependencies:
- dependency-name: sigstore/cosign-installer
  dependency-version: 398d4b0eeef1380460a10c8013a76f728fb906ac
  dependency-type: direct:production
...

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

Author: dependabot[bot]

.github/workflows/release.yml

@@ -441,7 +441,7 @@ jobs:
 
       # ── Sigstore cosign signing ──────────────────────────────
       - name: Install cosign
-        uses: sigstore/cosign-installer@f713795cb21599bc4e5c4b58cbad1da852d7eeb9 # v3
+        uses: sigstore/cosign-installer@398d4b0eeef1380460a10c8013a76f728fb906ac # v3
 
       - name: Sign release artifacts with cosign
         run: |