dokku: Getting error when installing dokku in a brand new linode box (ubuntu 18.04)

I’ve been trying to install dokku on linode in a brand new box with ubuntu 18.04 but I couldn’t get to finish the installation successfully. I’ve ran the commands on dokku’s main page in order to install it: http://dokku.viewdocs.io/dokku/

Am I missing something? Thanks in advance

How reproducible:

Steps to Reproduce:

1. Create a new box with ubuntu 18.04 image.
2. Run: apt-get update
3. Download bootstra.sh with wget https://raw.githubusercontent.com/dokku/dokku/v0.12.5/bootstrap.sh
4. Run DOKKU_TAG=v0.12.5 bash bootstrap.sh

Result:

root@localhost:~# DOKKU_TAG=v0.12.5 bash bootstrap.sh
Preparing to install v0.12.5 from https://github.com/dokku/dokku.git...
--> Ensuring we have the proper dependencies
--> Initial apt-get update
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LC_CTYPE = "UTF-8",
        LANG = "en_US"
    are supported and installed on your system.
perl: warning: Falling back to a fallback locale ("en_US").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
Selecting previously unselected package apt-transport-https.
(Reading database ... 66600 files and directories currently installed.)
Preparing to unpack .../apt-transport-https_1.6.1_all.deb ...
Unpacking apt-transport-https (1.6.1) ...
Setting up apt-transport-https (1.6.1) ...
--> Installing docker
# Executing docker install script, commit: 36b78b2
2018-05-10 18:52:26 URL:https://get.docker.com/ [13847/13847] -> "-" [1]
+ sh -c apt-get update -qq >/dev/null
+ sh -c apt-get install -y -qq apt-transport-https ca-certificates curl >/dev/null
+ sh -c curl -fsSL "https://download.docker.com/linux/ubuntu/gpg" | apt-key add -qq - >/dev/null
Warning: apt-key output should not be parsed (stdout is not a terminal)
+ sh -c echo "deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic edge" > /etc/apt/sources.list.d/docker.list
+ [ ubuntu = debian ]
+ sh -c apt-get update -qq >/dev/null
+ sh -c apt-get install -y -qq --no-install-recommends docker-ce >/dev/null
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LC_CTYPE = "UTF-8",
        LANG = "en_US"
    are supported and installed on your system.
perl: warning: Falling back to a fallback locale ("en_US").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
+ sh -c docker version
Client:
 Version:      18.05.0-ce
 API version:  1.37
 Go version:   go1.9.5
 Git commit:   f150324
 Built:        Wed May  9 22:16:13 2018
 OS/Arch:      linux/amd64
 Experimental: false
 Orchestrator: swarm

Server:
 Engine:
  Version:      18.05.0-ce
  API version:  1.37 (minimum version 1.12)
  Go version:   go1.9.5
  Git commit:   f150324
  Built:        Wed May  9 22:14:23 2018
  OS/Arch:      linux/amd64
  Experimental: false
If you would like to use Docker as a non-root user, you should now consider
adding your user to the "docker" group with something like:

  sudo usermod -aG docker your-user

Remember that you will have to log out and back in for this to take effect!

WARNING: Adding a user to the "docker" group will grant the ability to run
         containers which can be used to obtain root privileges on the
         docker host.
         Refer to https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface
         for more information.
--> Installing dokku
2018-05-10 18:53:21 URL:https://packagecloud.io/gpg.key [3889/3889] -> "-" [1]
OK
deb https://packagecloud.io/dokku/dokku/ubuntu/ bionic main
E: Unable to correct problems, you have held broken packages