Switch from YAML to YAML::XS in tools/update-responses/update_responses

In the script tools/update-responses/update_responses we use the YAML perl module. However on https://metacpan.org/pod/YAML we can read: If you want robust and fast YAML processing using the normal Dump/Load API, please consider switching to YAML::XS. It is by far the best Perl module for YAML at this time.

So we should probably switch to YAML::XS. We are already using YAML::XS in rbm.