Update Gemfile.lock using Docker without Ruby installed locally

update-gemfile-lock.sh

#!/bin/bash
if [ ! -f ./Gemfile.lock ]; then
  # No Gemfile.lock present, create a new one
  touch Gemfile.lock
fi
if [ -f ./.ruby-version ]; then
  ruby_version="$(cat .ruby-version)"
else
  ruby_version="latest"
fi
docker run \
  --mount type=bind,source="$(pwd)/Gemfile",target=/Gemfile \
  --mount type=bind,source="$(pwd)/Gemfile.lock",target=/Gemfile.lock \
  ruby:${ruby_version} \
  bundle lock --update