style: use -n flag in head and tail commands (#10391)

Co-authored-by: Marc Cornellà <hello@mcornella.com>

lib/diagnostics.zsh

@@ -335,7 +335,7 @@ function _omz_diag_dump_os_specific_version() {
       builtin echo "OS Version: $osname $osver build $(sw_vers -buildVersion)"
       ;;
     cygwin)
-      command systeminfo | command head -4 | command tail -2
+      command systeminfo | command head -n 4 | command tail -n 2
       ;;
   esac