Bump debian from trixie-20260406 to trixie-20260421 in /.github/docker#2429

pkwarren merged 1 commit intomainbufbuild/plugins:mainfrom

dependabot/docker/dot-github/docker/debian-trixie-20260421bufbuild/plugins:dependabot/docker/dot-github/docker/debian-trixie-20260421Copy head branch name to clipboard