[llvm] [mlir][spv] Enable spirv-tests CI to run for mlir-spv target tests (PR #152124)

[Davide Grohmann via llvm-commits]

davidegrohmann wrote:

> I'm wondering if it would be better to bifurcate `spirv-tests.yml` and have a separate version for mlir-spirv. It's very rare that we have PRs that affect both implementations, so having them separate could save us some CI time.

Yes it is likely better. This is now done.

https://github.com/llvm/llvm-project/pull/152124