DICOM-Atlas v0.2.5

Fixed

• CITATION.cff: split compound Apache-2.0 AND CC0-1.0 into a CFF
  list; CFF v1.2.0 does not allow compound SPDX expressions and Zenodo
  rejected the v0.2.4 deposit with "Citation metadata load failed".
• CITATION.cff: correct stale repository-code, url, and
  license-url values left over from the DicomAtlas -> DICOM-Atlas
  organisation rename.
• CITATION.cff: bump version / date-released to reflect 0.2.4 release.

Full Changelog: v0.2.4...v0.2.5