Bump blue-build/github-action from 1.7 to 1.8

Bumps [blue-build/github-action](https://github.com/blue-build/github-action) from 1.7 to 1.8.
- [Release notes](https://github.com/blue-build/github-action/releases)
- [Changelog](https://github.com/blue-build/github-action/blob/main/CHANGELOG.md)
- [Commits](blue-build/github-action@v1.7...v1.8)

---
updated-dependencies:
- dependency-name: blue-build/github-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/build.yml

@@ -28,7 +28,7 @@ jobs:
     steps:
       # the build is fully handled by the reusable github action
       - name: Build Custom Image
-        uses: blue-build/github-action@v1.7
+        uses: blue-build/github-action@v1.8
         with:
           recipe: ${{ matrix.recipe }}
           cosign_private_key: ${{ secrets.SIGNING_SECRET }}