logstash: Fix version scheme
logstash: Fix version scheme

This matches production and avoid apt-get error during deployment [1]

[1] https://forge.softwareheritage.org/P293

SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site