docker: add ppc64le support

Thanks to OSU Open Source Lab for making this possible

.github/workflows/docker.yml

@@ -111,7 +111,7 @@ jobs:
         uses: docker/build-push-action@v2
         with:
           file: ./${{ steps.info.outputs.dockerfile }}
-          platforms: linux/amd64,linux/arm64
+          platforms: linux/amd64,linux/arm64,linux/ppc64le
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.info.outputs.tags }}
           build-args: |