libvirt: add missing 'ssh' to $PATH

Fixes this error when trying to migrate a VM using Connectivity Mode
Tunneled:

  Unable to migrate guest: Cannot find 'ssh' in path: No such file or directory

Fixes https://github.com/NixOS/nixpkgs/issues/221815

pkgs/development/libraries/libvirt/default.nix

@@ -22,6 +22,7 @@
 , makeWrapper
 , meson
 , ninja
+, openssh
 , perl
 , perlPackages
 , polkit
@@ -91,6 +92,7 @@ let
     lvm2
     numactl
     numad
+    openssh
     pmutils
     systemd
   ] ++ lib.optionals enableIscsi [