Bump Bazel version to 8.3.1, migrate to bzlmod and bump LLVM to latest

[SihaoLiu]

Hi @j2kun

Thank you so much for your very helpful tutorial on MLIR. I really enjoy reading your words and really learn from you.

I found the bazel version is a little bit old, so I upgrade it to bazel 8.3.1 and migrate most of dependency to bzlmod.

I also bump LLVM version to latest as today (July 17, 2025)

Thank you again for providing such valuable tutorial

[j2kun]

This is helpful! I did not previously know how to put the llvm configuration part in MODULE.bazel, despite having done this migration on my main MLIR project (google/heir) already.

Can you also remove the bazel/import_llvm.bzl and related files that are no longer used?

[j2kun]

If you rebase over main you should get the fixes to the github action

[SihaoLiu]

If you rebase over main you should get the fixes to the github action

Thanks will do. I also bump the LLVM version to latest but haven't really finished. Will absorb all your comments later

[SihaoLiu]

If you rebase over main you should get the fixes to the github action

Do you mind taking another look? Building seems work on my local machine. I also bump the LLVM to the latest version with some fixes in original code. hope I adopted all your suggestions.

[SihaoLiu]

@j2kun I believe this CI failure (56697c4) is caused by CI's yml file still try to use bazel/import_llvm.bzl and the submodule commit hash is not updated. I already fixed it. Can you kick off CI again?

[j2kun]

LGTM, just waiting for CI to pass

[SihaoLiu]

LGTM, just waiting for CI to pass

Thanks! I think CI passed and really happy to contribute. 😃