chore(release): bump version to 6.2.7 (#473)

Ships the ISSUE-152 fix from #471: five update methods
(update_annotation, update_context_event, update_schema_type,
update_schema_attribute, update_subject_area) now send their body.

Signed-off-by: Dan Wolfson <dan.wolfson@pdr-associates.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: dwolfson