Support for 4.5 Schema

[tmorrell]

We should support the DataCite 4.5 Schema. https://doi.org/10.5438/jvkk-8198

### Tasks
- [ ] Transfer over starting schema from @mfenner https://github.com/front-matter/commonmeta-py/blob/main/commonmeta/resources/datacite-v45.json
- [ ] Transfer all example 4.5 files from https://schema.datacite.org/meta/kernel-4.5/
- [ ] Resolve doi/identifiers https://github.com/inveniosoftware/datacite/issues/80
- [ ] Check if anything in https://github.com/inveniosoftware/datacite/issues/35 is relevant