Varnish Cache VMOD using the synchronous libvalkey library API to access Valkey servers from VCL.

This project is basically a sibling of the redis VMOD: same API, same features, but built for Valkey instead of Redis. I kicked this off after the whole Redis licensing mess in March 2024, but put it on hold in May 2025 when Redis went back to an open-source license starting with version 8.0.