Don't push to registry when using GH attestations (#31)

Let's just show the attestations themselves

Author: jhrozek

.github/workflows/build-image-signed-ghat-malicious.yml

@@ -38,4 +38,3 @@ jobs:
         with:
           subject-name: ghcr.io/${{ github.repository }}
           subject-digest: ${{ steps.push-step.outputs.digest }}
-          push-to-registry: true

.github/workflows/build-image-signed-ghat-static-copied.yml

@@ -35,4 +35,3 @@ jobs:
         with:
           subject-name: ghcr.io/${{ github.repository }}
           subject-digest: ${{ steps.push-step.outputs.digest }}
-          push-to-registry: true

.github/workflows/build-image-signed-ghat-static.yml

@@ -35,4 +35,3 @@ jobs:
         with:
           subject-name: ghcr.io/${{ github.repository }}
           subject-digest: ${{ steps.push-step.outputs.digest }}
-          push-to-registry: true

.github/workflows/build-image-signed-ghat.yml

@@ -34,4 +34,3 @@ jobs:
         with:
           subject-name: ghcr.io/${{ github.repository }}
           subject-digest: ${{ steps.push-step.outputs.digest }}
-          push-to-registry: true