explicit lockfiles no longer sorted

[minrk]

Running the same test as #170, but with --kind explicit results in a different hash on every run:

env_file=/tmp/environment.yml
lock_file=/tmp/conda-explicit.lock

cat << EOF > $env_file
channels:
  - conda-forge

dependencies:
  - scikit-learn
EOF

function conda_lock_multiple_times() {
    rm -rf $lock_file
    for i in $(seq 1 4); do
        conda-lock lock -k explicit --mamba -p linux-64 -f $env_file --filename-template $lock_file > /dev/null 2>&1
        echo "lock file md5sum: $(md5 $lock_file)"
    done
}

echo "first run"
conda_lock_multiple_times

echo "second run"
conda_lock_multiple_times

0.13.2 produces consistent output everytime, while 1.0.1 and 1.0.4 produce different hashes on every run. I presume the fix is similar to #181, but on a different code path.