PoCL: Upstream Julia CI fails

> Hi, we have recently encountered a bunch of failing Julia workflows like [this one](https://github.com/pocl/pocl/actions/runs/21636567643/job/62363642274?pr=2117). They have some things in common, AFAICT it's always Julia 1.10, the job runs on Zen4 CPU (AMD EPYC 9V74) and fail with `Invalid instruction at `. I've tried to reproduce locally with AVX-512 machine, but all the tests pass for me, and i can't really spend much time on debugging this. Have you seen this issue ? Is this a Julia 1.10 specific bug related to AVX512 ? Unfortunately i don't think we can limit the CPU in Github-hosted runners, however we could try using a self-hosted runner.

_Originally posted by @franz in https://github.com/pocl/pocl/issues/2117#issuecomment-3842302978_