Release prep v3.20.0

[github-actions[bot]]

Automated release-prep through pdk-templates from commit 9cb918efcd8ff0ae6d2a011bd1da2bd26f050877. 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