Homebrew cask is not published on release and goes stale on the tap

[mmanciop]

Problem

Since the Homebrew formula-to-cask migration, tagged releases no longer update the cask in the dedicated tap repository dash0hq/homebrew-dash0-cli. The release pipeline publishes the GitHub release, the container images, and the legacy formula successfully, and only then fails when it tries to update the cask — so the run finishes red but most artifacts are already out, which made the failure easy to miss.

The cask update step fails with a 404 Not Found when writing to the separate tap repository, while the same-repository formula push in the same run succeeds. The effective cause is that the release pipeline's credentials cannot write to dash0hq/homebrew-dash0-cli. The cask currently on the tap was last published manually, so it is several releases behind.

User-facing behavior

• Users who installed via the cask (brew install --cask dash0hq/dash0-cli/dash0) do not receive updates — brew upgrade --cask dash0 keeps them pinned to the last manually published version.
• New releases are effectively not installable through the cask path advertised in the README and the migration notes.
• This compounds with Brew cask installation fails on Linux #172: the stale cask also still contains the macOS-only post-install hook that breaks Linux installs.

Acceptance criteria

• A tagged release publishes an updated Casks/dash0.rb to dash0hq/homebrew-dash0-cli matching the released version.
• The Release workflow completes successfully, with no 404 on the cask publish step.
• brew upgrade --cask dash0 picks up the newly released version on macOS and Linux.

Related: #172