testing/vosk-api: add back one-thread patch

Someone said numen was much slower on postmarketOS than Mobian and was maxing out all their cores. I updated my system and found the same and OPENBLAS_NUM_THREADS=1 numen fixed it. I had been using the version before this patch was removed. Although it doesn't segfault without this patch now that openblas is fixed (thank you!), I still think this patch is important and intended, the vosk devs set the same but with flags at compile time.

Also made a pull request: https://github.com/alphacep/vosk-api/pull/1414