Resolved SyntaxError on Ruby 2.7
Resolved SyntaxError on Ruby 2.7

```
SyntaxError:
  /home/runner/work/gitlab_mr_release/gitlab_mr_release/vendor/bundle/ruby/2.7.0/gems/unparser-0.1.14/lib/unparser/emitter.rb:421: circular argument reference - body
```

https://github.com/sue445/gitlab_mr_release/pull/36/checks?check_run_id=369851535

sue445/gitlab_mr_release,sue445/gitlab_mr_release,sue445/gitlab_mr_release