Updating cosign to try to fix docker image action (#60)

See if updating the cosing version in the action fixes the issue.

.github/workflows/docker-publish.yml

@@ -36,9 +36,9 @@ jobs:
       # https://github.com/sigstore/cosign-installer
       - name: Install cosign
         if: github.event_name != 'pull_request'
-        uses: sigstore/cosign-installer@7e0881f8fe90b25e305bbf0309761e9314607e25
+        uses: sigstore/cosign-installer@f3c664df7af409cb4873aa5068053ba9d61a57b6 #v2.6.0
         with:
-          cosign-release: 'v1.9.0'
+          cosign-release: 'v1.11.0'
 
 
       # Workaround: https://github.com/docker/build-push-action/issues/461
@@ -74,9 +74,11 @@ jobs:
         uses: docker/build-push-action@ac9327eae2b366085ac7f6a2d02df8aa8ead720a
         with:
           context: .
-          push: true
+          push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
 
       # Sign the resulting Docker image digest except on PRs.
       # This will only write to the public Rekor transparency log when the Docker
@@ -89,4 +91,4 @@ jobs:
           COSIGN_EXPERIMENTAL: "true"
         # This step uses the identity token to provision an ephemeral certificate
         # against the sigstore community Fulcio instance.
-        run: cosign sign ${{ steps.meta.outputs.tags }}@${{ steps.build-and-push.outputs.digest }}
+        run: echo "${{ steps.meta.outputs.tags }}" | xargs -I {} cosign sign {}@${{ steps.build-and-push.outputs.digest }}