Postal quick installation fix

install_postal.sh

#!/bin/bash

# This will install everything required to run a basic Postal installation.
# This should be run on a clean Ubuntu 16.04 server.
#
# Once the installation has completed you will be able to access the Postal web
# interface on port 443. It will have a self-signed certificate.
#
# * Change the MySQL & RabbitMQ passwords
# * Create your first admin user with 'postal make-user'
# * Replace the self-signed certificate in /etc/nginx/ssl/postal.cert
# * Make appropriate changes to the configuration in /opt/postal/config/postal.yml
# * Setup your DNS                          [ https://github.com/atech/postal/wiki/Domains-&-DNS-Configuration ]
# * Configure the click & open tracking     [ https://github.com/atech/postal/wiki/Click-&-Open-Tracking ]
# * Configure spam & virus checking         [ https://github.com/atech/postal/wiki/Spam-&-Virus-Checking ]

set -e

#
# Dependencies
#
apt update
apt install -y software-properties-common
apt-add-repository ppa:brightbox/ruby-ng -y
apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xF1656F24C74CD1D8


sudo apt-get update -y
## Install prerequisites
sudo apt-get install curl gnupg -y
## Install RabbitMQ signing key
curl -fsSL https://github.com/rabbitmq/signing-keys/releases/download/2.0/rabbitmq-release-signing-key.asc | sudo apt-key add -
## Install apt HTTPS transport
sudo apt-get install apt-transport-https
## Add Bintray repositories that provision latest RabbitMQ and Erlang 21.x releases
sudo tee /etc/apt/sources.list.d/bintray.rabbitmq.list <<EOF
## Installs the latest Erlang 22.x release.
## Change component to "erlang-21.x" to install the latest 21.x version.
## "bionic" as distribution name should work for any later Ubuntu or Debian release.
## See the release to distribution mapping table in RabbitMQ doc guides to learn more.
deb https://dl.bintray.com/rabbitmq-erlang/debian bionic erlang
deb https://dl.bintray.com/rabbitmq/debian bionic main
EOF
## Update package indices
sudo apt-get update -y
## Install rabbitmq-server and its dependencies
sudo apt-get install rabbitmq-server -y --fix-missing


export DEBIAN_FRONTEND=noninteractive
apt install -y ruby2.3 ruby2.3-dev build-essential libssl-dev mariadb-server libmysqlclient-dev rabbitmq-server nodejs git nginx wget nano
gem install bundler procodile --no-rdoc --no-ri

#
# MySQL
#
echo 'CREATE DATABASE `postal` CHARSET utf8mb4 COLLATE utf8mb4_unicode_ci;' | mysql -u root
echo 'GRANT ALL ON `postal`.* TO `postal`@`127.0.0.1` IDENTIFIED BY "p0stalpassw0rd";' | mysql -u root
echo 'GRANT ALL PRIVILEGES ON `postal-%` . * to `postal`@`127.0.0.1`  IDENTIFIED BY "p0stalpassw0rd";' | mysql -u root

#
# RabbitMQ
#
rabbitmqctl add_vhost /postal
rabbitmqctl add_user postal p0stalpassw0rd
rabbitmqctl set_permissions -p /postal postal ".*" ".*" ".*"

#
# System prep
#
useradd -r -m -d /opt/postal -s /bin/bash postal
setcap 'cap_net_bind_service=+ep' /usr/bin/ruby2.3

#
# Application Setup
#
sudo -i -u postal mkdir -p /opt/postal/app
wget https://postal.atech.media/packages/stable/latest.tgz -O - | sudo -u postal tar zxpv -C /opt/postal/app
ln -s /opt/postal/app/bin/postal /usr/bin/postal
postal bundle /opt/postal/vendor/bundle
postal initialize-config
postal initialize
postal start

#
# nginx
#
cp /opt/postal/app/resource/nginx.cfg /etc/nginx/sites-available/default
mkdir /etc/nginx/ssl/
openssl req -x509 -newkey rsa:4096 -keyout /etc/nginx/ssl/postal.key -out /etc/nginx/ssl/postal.cert -days 365 -nodes -subj "/C=GB/ST=Example/L=Example/O=Example/CN=example.com"
service nginx reload

#
# All done
#
echo
echo "Installation complete"

& when I tried for the second time it says the same:

Reading package lists... Done
E: The repository 'http://www.rabbitmq.com/debian testing Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.