Cerbos PDP v0.54.0: Faster evaluations, lower memory usage, and new store diagnostics

Cerbos PDP v0.54.0 focuses on performance, cutting steady-state memory and raising throughput. This release adds the new cerbos compile-store command for diagnosing policy stores, clearer error reporting across policies and tests, automatic GOMEMLIMIT from cgroup limits, and better runtime observability.