Bump sigstore/cosign-installer from 2.7.0 to 2.8.0

Bumps [sigstore/cosign-installer](https://github.com/sigstore/cosign-installer) from 2.7.0 to 2.8.0.
- [Release notes](https://github.com/sigstore/cosign-installer/releases)
- [Commits](sigstore/cosign-installer@v2.7.0...v2.8.0)

---
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/golang.yml

@@ -81,7 +81,7 @@ jobs:
           check-latest: true
 
       - name: Install cosign
-        uses: sigstore/cosign-installer@v2.7.0
+        uses: sigstore/cosign-installer@v2.8.0
         with:
           cosign-release: 'v1.12.1'
 
@@ -160,7 +160,7 @@ jobs:
           GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
 
       - name: Install cosign
-        uses: sigstore/cosign-installer@v2.7.0
+        uses: sigstore/cosign-installer@v2.8.0
         with:
           cosign-release: 'v1.12.1'
 
@@ -196,7 +196,7 @@ jobs:
 
     steps:
       - name: Install cosign
-        uses: sigstore/cosign-installer@v2.7.0
+        uses: sigstore/cosign-installer@v2.8.0
         with:
           cosign-release: 'v1.12.1'