fix(command-not-found): remove invalid argument for PackageKit (#9876)

`pk-command-not-found` doesn't accept `--` as an argument. This is what happens when `--` is the first argument:

```
$  gem
zsh: --: command not found...
```

plugins/command-not-found/command-not-found.plugin.zsh

@@ -38,7 +38,7 @@ fi
 if [[ -x /usr/libexec/pk-command-not-found ]]; then
   command_not_found_handler() {
     if [[ -S /var/run/dbus/system_bus_socket && -x /usr/libexec/packagekitd ]]; then
-      /usr/libexec/pk-command-not-found -- "$@"
+      /usr/libexec/pk-command-not-found "$@"
       return $?
     fi