fix docker build yml

Author: austinabell

Diff for: .github/workflows/publish.yml

@@ -54,7 +54,8 @@ jobs:
         id: push
         uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
         with:
-          context: ./dockerfiles/blobstream0.Dockerfile
+          context: .
+          file: ./dockerfiles/blobstream0.Dockerfile
           push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}