build(deps): bump sigstore/cosign-installer from 2.7.0 to 2.8.1

Bumps [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) from 2.7.0 to 2.8.1.
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](sigstore/cosign-installer@v2.7.0...v2.8.1)

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

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

.github/workflows/goreleaser.yml

@@ -25,7 +25,7 @@ jobs:
       with:
         go-version: "1.18"
         check-latest: true
-    - uses: sigstore/cosign-installer@ced07f21fb1da67979f539bbc6304c16c0677e76 # tag=v2.7.0
+    - uses: sigstore/cosign-installer@9becc617647dfa20ae7b1151972e9b3a2c338a2b # tag=v2.8.1
     - name: Set up QEMU
       uses: docker/setup-qemu-action@e81a89b1732b9c48d79cd809d8d81d79c4647a18 # tag=v2.1.0
     - name: Docker login