refactor: use -qq flat with apt-get (djordon#12)

* Revert recent use of --quiet

refactor: be a quieter action (djordon#11)

* Make `apt-get clean` and `git fetch` quiet

fix: make sure script exits early on duplicate tags (djordon#10)

* Update the script to make sure that variables are quoted in regular POSIX compliant `test`.
* Remove unnecessary echo in script

refactor: update README and the default command (djordon#9)

* Change the default command to look at the contents of a `VERSION` file.
* Send errors of `VERSION_COMMAND` to `/dev/null`.
* Update the version of ubuntu used (in both the `Dockerfile` and the Github action).
* Allow user to configure whether `v` is prepended to the output of the `VERSION_COMMAND`.
* Update the README

Exit status 1 on bad command (djordon#8)

* Return status code 1 when the version command yields an empty response

Fix typo in default version command

Simplify the mix config

Clean up repo (djordon#6)

* Move files to the root of the repository
* Use master as the action
* Make the version 0.1.0

Bump the version to 0.0.1