Update builder and stack heroku-22

.github/workflows/docker-publish.yml

@@ -46,7 +46,7 @@ jobs:
         [[ ! -z  $(yq e '. | keys' Procfile | cut -c 3- | grep bash) ]] \
         || echo 'bash: bash -l' >> Procfile
         pack build "ghcr.io/hvg/blog:$TAG" \
-          --builder heroku/buildpacks:20 \
+          --builder heroku/builder-classic:22 \
           --descriptor project.toml \
           --workspace /app \
           --env COMPOSER_AUTH=$COMPOSER_AUTH;