Add s390x to build automation

Author: Joshua-Beha

Diff for: .github/workflows/build-test-publish.yml

@@ -106,7 +106,7 @@ jobs:
       uses: docker/build-push-action@v3
       with:
         context: .
-        platforms: linux/amd64, linux/arm64
+        platforms: linux/amd64, linux/arm64, linux/s390x
         push: ${{ github.event_name != 'pull_request' }}
         tags: ${{ steps.meta.outputs.tags }}
         labels: ${{ steps.meta.outputs.labels }}