nixos/wyoming/piper: relax ProcSubset to all

The onnxruntime library wants to query cpuinfo, which fails when the proc
subset is restricted.

Close: #445723

nixos/modules/services/home-automation/wyoming/piper.nix

···
             ProtectKernelTunables = true;
             ProtectControlGroups = true;
             ProtectProc = "invisible";
-            ProcSubset = "pid";
+            ProcSubset = "all"; # for onnxruntime, which queries cpuinfo
             RestrictAddressFamilies = [
               "AF_INET"
               "AF_INET6"