Update to 0.019. From the changelog:

- Important (and possibly breaking) changes:
  - Change default schema from JSON to Core.
    Reason: This is the recommended Schema for YAML 1.2, and what people
    would expect to be the default.
  - load* in scalar context returns first document.
    Reason: I think this is the most reasonable behaviour, and it
    will continue to work the same if you later add documents to a file.
  - Empty nodes in YAML 1.2 JSON Schema resolve to '' by default like
    before, but now it can be configured
  - Fix some control character escaping and encoding issues (issue#16, issue#17)
    YAML::PP will now just assume all input data are unicode characters
    and won't do an explicit utf8::upgrade
  - Fix Core schema resolver for inf: add +.inf, +.Inf, +.INF
- Improve emitter regarding empty lists/hashes (no newline before []/{})
- Spelling and grammar fixes (PR#23 @gregoa)
- Fix YAML::PP::Grammar pod (PR#22 @gregoa)
- Fix yamlpp5-load-dump
- Fix error tokens output
- Update yaml-test-suite to data-2020-02-11

(schmonz)