[llvm] [bazel] update .bazelversion to 8.0.0 (PR #119425)

[Nick Desaulniers via llvm-commits]

nickdesaulniers wrote:

https://github.com/bazelbuild/rules_python/releases/tag/1.0.0 yep that does it!

https://github.com/llvm/llvm-project/pull/119425