databases/postgresql16-*: Update to 16.0

The PostgreSQL Global Development Group today announced the release of
PostgreSQL 16, the latest version of the world's most advanced open
source database.

PostgreSQL 16 raises its performance, with notable improvements to query
parallelism, bulk data loading, and logical replication. There are many
features in this release for developers and administrators alike,
including more SQL/JSON syntax, new monitoring stats for your workloads,
and greater flexibility in defining access control rules for management
of policies across large fleets.

Read about more improvements in the release notes, for example about
Performance Improvements, Logical replication, Developer Experience,
Access Control & Security and Monitoring.

Release notes: https://www.postgresql.org/about/news/postgresql-16-released-2715/