This is failing to validate sm6 -> spirv on the last test in cbuffer.shader_test, but it doesn't fail locally, which is confusing. I don't suppose anyone has a hint?
Without knowing your exact local setup, SPIR-V validation depends on both building vkd3d-shader against SPIRV-Tools and having VKD3D_SHADER_CONFIG=force_validation in the environment when running the tests. Do you have both of those? My other guess would be subtle differences in the versions of SPIRV-Tools and/or dxcompiler between what you have locally and what's on the CI.