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

[Oleksandr Alex Zinenko via llvm-commits]

ftynse wrote:

Some sort of public documentation on what exactly are the images and how to update those (even if it involves filing an issue an assigning that to specific people) is needed IMO. Specifically, I'm thinking of the case where MLIR bumps python/pybind11/numpy version and the image need to be updated in order for that change to land.

Otherwise I'm happy to have this!

(cc @joker-eph )

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