nginx/logrotate: run logrotate as nginx user

nixos/modules/services/web-servers/nginx/default.nix

@@ -992,6 +992,7 @@ in
     services.logrotate.settings.nginx = mapAttrs (_: mkDefault) {
       files = "/var/log/nginx/*.log";
       frequency = "weekly";
+      su = "${cfg.user} ${cfg.group}";
       rotate = 26;
       compress = true;
       delaycompress = true;