chore(workflows): add auto-labeler step to release draft workflow

[tusharmath]

Summary

Add an auto-labeler step to the release-drafter workflow so that PRs are automatically labeled based on rules defined in release-drafter.yml.

Context

The release-drafter workflow previously only updated the release draft on pushes to main. PRs were not being automatically labeled, requiring manual label assignment before merging. The release-drafter action supports an autolabeler sub-action that reads label rules from the same config file and applies them to PRs on pull_request_target events.

Changes

• Added an "Auto Labeler" step to .github/workflows/release-drafter.yml that runs on pull_request_target events using release-drafter/autolabeler@v7
• Updated draft_release_update_job.rs in the forge_ci crate to include the corresponding auto-labeler step in the programmatically-generated workflow job

Key Implementation Details

The auto-labeler step is gated with if: github.event_name == 'pull_request_target' so it only fires for PR events and not for push events (which trigger the release draft update). Both the hand-authored YAML and the Rust-generated workflow are kept in sync.

Testing

# Verify the generated workflow matches the committed YAML
cargo insta test --accept -p forge_ci

# Manually open a PR against main and confirm labels are applied automatically
# based on the rules in .github/release-drafter.yml