chore(release): 1.0.0-alpha.6 [skip ci]

# [1.0.0-alpha.6](https://git.gitlab.arm.com/bazel/rules_download/compare/v1.0.0-alpha.5...v1.0.0-alpha.6) (2024-01-23)

### Bug Fixes

* **e2e:** change to BCR `toolchain_utils` ([5ac42bca](https://git.gitlab.arm.com/bazel/rules_download/commit/5ac42bca2d186bb9f8cbe38bb5182f5d0ff6a5f7))