Vector v0.39.0 release

[jszwedko]

The week before the release:

• Check for any outstanding deprecation actions in DEPRECATIONS.md and
  take them (or have someone help you take them)
• Create a new release branch from master to freeze commits
  • git fetch && git checkout origin/master && git checkout -b v0.<new version number> && git push -u
• Create a new release preparation branch from master
  • git checkout -b prepare-v0.<new version number> && git push -u
• Check if there is a newer version of Alpine or Debian available to update the release images
  in distribution/docker/. Update if so.
• Run cargo vdev build release-cue to generate a new cue file for the release
  • Add description key to the generated cue file with a description of the release (see
    previous releases for examples).
  • Ensure any breaking changes are highlighted in the release upgrade guide
  • Ensure any deprecations are highlighted in the release upgrade guide
• Update version number in website/cue/reference/administration/interfaces/kubectl.cue
• Update version number in distribution/install.sh
• Add new version to website/cue/reference/versions.cue
• Create new release md file by copying an existing one in ./website/content/en/releases/ and
  updating version number
• Commit these changes
• Open PR against the release branch (v0.<new version number>) for review
• PR approval

On the day of release:

• Rebase the release preparation branch on the release branch
  • Squash the release preparation commits (but not the cherry-picked commits!) to a single
    commit. This makes it easier to cherry-pick to master after the release. 
  • Ensure release date in cue matches current date.
• Merge release preparation branch into the release branch
  • git co v0.<new version number> && git merge --ff-only prepare-v0.<new version number>
• Tag new release
  • git tag v0.<minor>.0 -a -m v0.<minor>.0
  • git push origin v0.<minor>.0
• Wait for release workflow to complete
  • Discoverable via https://github.com/timberio/vector/actions/workflows/release.yml
• Release Linux packages. See vector-release usage.
• Release updated Helm chart. See releasing Helm chart.
• Once Helm chart is released, updated Vector manifests
  • Run cargo vdev build manifests and open a PR with changes
• Add docker images to https://github.com/DataDog/images to have them available internally.
• Cherry-pick any release commits from the release branch that are not on master, to master
• Bump the release number in the Cargo.toml on master to the next major release
• Reset the website branch to the HEAD of the release branch to update https://vector.dev
  • git checkout website && git reset --hard origin/v0.<new version number> && git push
• Kick-off post-mortems for any regressions resolved by the release