Re-enable linux/arm64 on demo image

Author: manics

.github/workflows/build.yml

@@ -210,10 +210,7 @@ jobs:
           build-args: |
             BASE_IMAGE=${{ fromJson(steps.onbuildtags.outputs.tags)[0] }}
           context: demo-image
-          # linux/arm64 currently fails:
-          # ERROR: Could not build wheels for argon2-cffi which use PEP 517 and cannot be installed directly
-          # ERROR: executor failed running [/bin/sh -c python3 -m pip install notebook]: exit code: 1
-          platforms: linux/amd64
+          platforms: linux/amd64,linux/arm64
           push: true
           tags: ${{ join(fromJson(steps.demotags.outputs.tags)) }}
           cache-from: ${{ env.CACHE_FROM }}