I don't usually develop PHP; how can I update composer.lock?

I have a PHP scraper whose dependencies haven’t been touched in a long time. I need to update them, but I don’t normally work on PHP so I don’t have a PHP dev environment set up. Is there some way I can run composer update without needing to set up a full dev environment? I’d be happy using Docker if that makes things easier.

I solved this by creating update.sh in my scraper repo and running it.

if [ -e /.dockerenv ]; then
    if [ ! -e /app/.heroku ]; then
        herokuish buildpack build
    export PATH=/app/.heroku/php/bin/:$PATH
    cd /app
    composer update
    docker run -it -v ${PWD}:/app openaustralia/buildstep:early_release bash -x /app/update.sh
    sudo chown -R $(id -u):$(id -g) .