Fail to parse simple yaml file

File exmplae:
```test:
  - name: asd
    back:
    - img: qweqwe
      offset: qweqwe
````
Error message:
```
Yaml.Yaml.ResultError.message(Optional("expected dedent, near \"offset: qweqwe\\n\\n\""))
```
Steps:
1) Install YamlSwift with Pods (added pod 'Yaml' to Podfile)
2) Changed swift language to swift 4 (it doesn't compiles in swift5)
3) Try to load example above