Release prep v15.0.0

[github-actions[bot]]

Automated release-prep through pdk-templates from commit db5086e3c2cf857b51b22907d5dc4d77bc1dcc06. 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