cleanup: Remove expired puppet6 ports:
2023-06-01 sysutils/puppet6: Puppet 6 has reached EOL
2023-06-01 sysutils/puppetserver6: Puppet 6 has reached EOL
2023-06-01 databases/puppetdb6: Puppet 6 has reached EOL
2023-06-01 databases/puppetdb-terminus6: Puppet 6 has reached EOL