Release prep v6.0.0

[github-actions[bot]]

Automated release-prep through pdk-templates from commit c992e28eaccfe1ffd0e91dcc0f0a9ee9f99f400d. Please verify before merging:

• [x] last nightly run is green
• [x] Changelog is readable and has no unlabeled pull requests
• [x] Ensure the changelog version and metadata version match