rules_docker broken with Bazel@HEAD CI

[c-parsons]

Breakage:
https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/2211#a8703949-3bd7-4c71-bd75-d787de800fec

File "/var/lib/buildkite-agent/builds/bk-docker-80kl/bazel-downstream-projects/rules_docker/docker/toolchain_container/debian_pkg_tar.bzl", line 127, column 38, in _generate_deb_tar
--
  | _download_deb_pkgs.implementation(
  | File "/var/lib/buildkite-agent/builds/bk-docker-80kl/bazel-downstream-projects/rules_docker/docker/package_managers/download_pkgs.bzl", line 85, column 22, in _impl
  | packages = depset(packages or ctx.attr.packages)
  | Error in depset: parameter 'direct' must contain a list of elements, and may no longer accept a depset. The deprecated behavior may be temporarily re-enabled by setting --incompatible_disable_depset_items=false

Bazel instituted a change to semantics of depset(). This should be fixed in-place or you can temporarily use --incompatible_disable_depset_items=false to disable this restriction.

[mai93]

This still needs to be fixed as the project is still broken with Bazel at head:
https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/2243#65c204c9-bb46-42ba-9bf2-a9d999b4b0d6

[c-parsons]

Ping. This still needs to be fixed. Going to add some assignees for visibility ( Feel free tor reassign as appropriate)