Contributing with Docker in Arch Linux Service 'web' failed to build

[Phabbits]

I am trying to contribute on my Arch Linux machine using Docker Compose, but when I run sudo docker-compose build I am getting the error:
You must use Bundler 2 or greater with this lockfile.
ERROR: Service 'web' failed to build : The command 'bundle install' returned a non-zero code: 20

Here are the steps that I have taken in order to get started:

1. Install Docker on my Arch Linux (Arch Wiki)
   sudo pacman -Syu docker
sudo systemctl start docker
2. Install Docker-Compose (Docker Compose)
   sudo curl -L "https://github.com/docker/compose/releases/download/1.27.4/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose
3. Follow the quickstart with my own fork of edit.tosdr.org (Quick Start)
   git clone https://github.com/Phabbits/edit.tosdr.org.git
cd edit.tosdr.org
sudo sh INSTALL_linux.sh
4. Followed the Automated environment setup in the contributing guidelines
   sudo docker-compose build
   Get error listed on top

Attempt to solve:
Following this thread on the issue (Stack Overflow)
Updated Rubygems
sudo gem update --system
sudo gem install bundler
Add bundler to the path (Stack Overflow)
export PATH=$PATH:/home/your_username/.gem/ruby/2.7.0/bin
Attempt to update Gemfile.lock
sudo bundler update --bundler
Get error: Your Ruby version is 2.7.2, but your Gemfile specified 2.6.5

Any help would be appreciated

[JustinBack]

Sorry for the late reply. We have updated the ruby version in 0c3e989. Could you try it again? It uses ruby 2.7.2 by default now.