Bump prosemirror-schema-basic from 1.2.3 to 1.2.4

Bumps [prosemirror-schema-basic](https://github.com/prosemirror/prosemirror-schema-basic) from 1.2.3 to 1.2.4.
- [Changelog](https://github.com/ProseMirror/prosemirror-schema-basic/blob/master/CHANGELOG.md)
- [Commits](https://github.com/prosemirror/prosemirror-schema-basic/compare/1.2.3...1.2.4

)

---
updated-dependencies:
- dependency-name: prosemirror-schema-basic
  dependency-version: 1.2.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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