chore: Remove cosign stage from Docker publish GHA (ietf-tools#239)

.github/workflows/docker-publish.yml

@@ -31,15 +31,6 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
-      # 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@1e95c1de343b5b0c23352d6417ee3e48d5bcd422
-        with:
-          cosign-release: 'v1.4.0'
-
-
       # Workaround: https://github.com/docker/build-push-action/issues/461
       - name: Setup Docker buildx
         uses: docker/setup-buildx-action@79abd3f86f79a9d68a23c75a09a9a85889262adf
@@ -74,16 +65,3 @@ jobs:
           push: ${{ github.event_name != 'pull_request' }}
           tags: ghcr.io/${{ github.repository }}:${{ github.event.release.tag_name }}, ghcr.io/${{ github.repository }}:latest
           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' }}
-        env:
-          COSIGN_EXPERIMENTAL: "true"
-        # This step uses the identity token to provision an ephemeral certificate
-        # against the sigstore community Fulcio instance.
-        run: cosign sign ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}@${{ steps.build-and-push.outputs.digest }}