changelog latest should work for unreleased projects

[mpkorstanje]

👓 What did you see?

# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](http://keepachangelog.com/)
and this project adheres to [Semantic Versioning](http://semver.org/).

## [Unreleased]

### Added
- First release of polyglot-release

mpkorstanje@Nyx:~/Projects/cucumber/polyglot-release$ changelog latest
Error: There are no released versions in the changelog yet
There are no released versions in the changelog yet
mpkorstanje@Nyx:~/Projects/cucumber/polyglot-release$ echo $?
1

By exiting with 1 we can not determine if there was a problem in the changelog or simply no version. This makes it impossible to use changelog in conjuction with automated tooling to make a first release (i.e. cucumber/polyglot-release#68).

✅ What did you expect to see?

Either exit code 0, and an empty string.

📦 Which tool/library version are you using?

Latest version I guess. But see: #11

[mattwynne]

There's some coupling here to be aware of:

https://github.com/cucumber/action-get-versions/blob/main/entrypoint.sh#L5 works around the current behaviour. If we change this, we could also simplify that code.