ci: remove signing

.github/actions/build-image/action.yml

@@ -18,14 +18,6 @@ inputs:
 runs:
   using: "composite"
   steps:
-    # Install the cosign tool except on PR
-    # https://github.com/sigstore/cosign-installer
-    - name: Install cosign
-      if: github.event_name != 'pull_request'
-      uses: sigstore/cosign-installer@7e0881f8fe90b25e305bbf0309761e9314607e25
-      with:
-        cosign-release: 'v1.9.0'
-
     # Workaround: https://github.com/docker/build-push-action/issues/461
     - name: Setup Docker buildx
       uses: docker/setup-buildx-action@79abd3f86f79a9d68a23c75a09a9a85889262adf
@@ -59,17 +51,3 @@ runs:
         push: ${{ github.event_name != 'pull_request' }}
         tags: ${{ steps.meta.outputs.tags }}
         labels: ${{ steps.meta.outputs.labels }}
-
-    # Sign the resulting Docker image digest except on PRs.
-    # This will only write to the public Rekor transparency log when the Docker
-    # repository is public to avoid leaking data.  If you would like to publish
-    # transparency data even for private images, pass --force to cosign below.
-    # https://github.com/sigstore/cosign
-    - name: Sign the published Docker image
-      if: ${{ github.event_name != 'pull_request' }}
-      shell: bash
-      env:
-        COSIGN_EXPERIMENTAL: "true"
-      # This step uses the identity token to provision an ephemeral certificate
-      # against the sigstore community Fulcio instance.
-      run: echo "${{ steps.meta.outputs.tags }}" | xargs -I {} cosign sign {}@${{ steps.build-and-push.outputs.digest }}