1.21.4

🐛 Bug Fixes

• Ensure retention timeout is always >= 5 (#660) @Vlatombe

📦 Dependency updates

• Bump bom-2.176.x from 3 to 4 (#646) @dependabot
• Bump plugin from 3.51 to 3.53 (#648) @dependabot

👻 Maintenance

• avoiding flake: RejectedAccessException: Scripts not permitted to use staticMethod org.jenkinsci.plugins.workflow.cps.Safepoint safepoint (#649) @jglick
• test-in-k8s.sh did not support Incrementals (#650) @jglick

🚦 Tests

• Setup namespace if needed and possible in declarative test (#654) @Vlatombe
• Safepoint flakes, redux (#655) @jglick