Bump sigstore/cosign-installer from 2.8.0 to 2.8.1 (ko-build#860)

Bumps [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) from 2.8.0 to 2.8.1.
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](sigstore/cosign-installer@v2.8.0...v2.8.1)

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

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

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

.github/workflows/image.yaml

@@ -19,7 +19,7 @@ jobs:
         with:
           go-version: 1.18
           check-latest: true
-      - uses: sigstore/cosign-installer@v2.8.0
+      - uses: sigstore/cosign-installer@v2.8.1
 
       # Build ko from HEAD, build and push an image tagged with the commit SHA,
       # then keylessly sign it with cosign.

.github/workflows/kind-e2e.yaml

@@ -35,7 +35,7 @@ jobs:
         registry-authority: ${{ env.REGISTRY_NAME }}:${{ env.REGISTRY_PORT }}
 
     - name: Install Cosign
-      uses: sigstore/cosign-installer@v2.8.0
+      uses: sigstore/cosign-installer@v2.8.1
       with:
         cosign-release: 'v1.7.2'
 

.github/workflows/sbom.yaml

@@ -115,7 +115,7 @@ jobs:
           unzip tools-java-${SPDX_TOOLS_VERSION}.zip
 
       - name: Install Cosign
-        uses: sigstore/cosign-installer@v2.8.0
+        uses: sigstore/cosign-installer@v2.8.1
         with:
           cosign-release: 'v1.7.2'