Merge pull request #551 from QIICR/dependabot/github_actions/github-a…

…ctions-02325a8da5

CI: Bump the github-actions group with 2 updates

Add CHANGELOG.md section for v1.5.6

Author the release notes ahead of tagging (per RELEASE.md): the Windows
zlib/deflate fix (#549) and the labelmap numbering/background docs (#548).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Merge pull request #547 from QIICR/docs/changelog-backfill

Add back-filled CHANGELOG.md and release-notes tooling

Merge pull request #536 from QIICR/Ft_itk2label

Add direct ITK to DICOM Labelmap conversion

Merge pull request #532 from QIICR/workflows-improvements

GitHub workflows improvements

Merge pull request #527 from fedorov/deprecate-scikit

Deprecate scikit, simplify release process

cmake: Set DCMQI version to 1.5.1

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>