Bug: ghcr images are lacking arm64

[samip5]

Describe the bug

The images provided in ghcr.io/foxcpp/maddy seem to lack arm64.

Steps to reproduce

1. Try to pull Maddy on arm64 host from ghcr.io.
2. See it fail due to manifest not including anything other than amd64

Log files

docker pull ghcr.io/foxcpp/maddy:0.8.1
0.8.1: Pulling from foxcpp/maddy
no matching manifest for linux/arm64/v8 in the manifest list entries

[cuihaoleo]

Same for docker.io images.