[llvm] [Github] Explicitly requesting Ubuntu 22.04 for SPIRV test (PR #122395)

[Adam Yang via llvm-commits]

adam-yang wrote:

Looks like there's a real problem with some spirv tests, maybe spirv-tools versions changed or something and is rejecting some SPIRV that was passing validation before.

https://github.com/llvm/llvm-project/pull/122395