[mlir] [llvm] [CI] Add check-mlir-python to MLIR pre-merge checks (PR #72847)

[Louis Dionne via llvm-commits]

ldionne wrote:

It's part of the image installed on the builders, and it's not something you control directly. Right now @metaflow is managing those images.

I think this is great though -- it shows that MLIR needs something slightly more specific than the monolithic CI setup we currently provide for most projects. This is what I suspected (i.e. that subprojects would have specific needs). Once we have runners able to take the load, we should move this to Github actions and then MLIR could define its own jobs that run appropriate checks and use appropriate dependencies.

https://github.com/llvm/llvm-project/pull/72847