agent-platform release v3.20.3

Changed

• (ats) Kind smoke with the auth and agent round trips, self-management adoption and CLI refusal against an in-cluster registry, the own-Flux scenario with the guard, and the ordered teardown in #307 by @teemow

Full Changelog: https://github.com/giantswarm/agent-platform/compare/v3.20.2...v3.20.3