loongson/pypi: links for vtk

INFO: Because this project isn't in the mirror_whitelist, no releases from root/pypi are included.

loongson/pypi vtk-9.2.6-cp39-cp39-linux_loongarch64.whl
loongson/pypi vtk-9.2.6-cp312-cp312-linux_loongarch64.whl
loongson/pypi vtk-9.2.6-cp310-cp310-linux_loongarch64.whl