Convert all remaining json manifests to yaml
    
    This conversion can be validated using this script:
    
     #!/bin/bash
    
    mkdir -p repo && cd repo && ostree init --repo . --mode=archive && cd ..
    variants=('silverblue' 'kinoite' 'xfce' 'lxqt')
    
    for v in ${variants[@]}; do
        sudo rpm-ostree compose tree --repo=repo --print-only fedora-$v.yaml > $v.yaml.out
    done
    
    git checkout --quiet HEAD~
    for v in ${variants[@]}; do
        sudo rpm-ostree compose tree --repo=repo --print-only fedora-$v.yaml > $v.json.out
    done
    
    for v in ${variants[@]}; do
        if [[ ! -z $(diff $v.json.out $v.yaml.out) ]]; then
            echo ""
            echo "$v: JSON != YAML"
            diff $v.json.out $v.yaml.out
            echo ""
            has_diff="true"
        fi
    done
    
    git checkout --quiet f30
    rm -rf ./repo
    for v in ${variants[@]}; do
        rm ./$v.json.out ./$v.yaml.out
    done
    
    if [[ $has_diff == "true" ]]; then
        echo "Found some diff!"
    else
        echo "OK!"
    fi