v1.6.0

CHANGES:

• Set the time zone of PostgreSQL connections to UTC to mitigate an
  undesirable implicit conversion to the local time zone for timestamp.
  This issue was exposed by the specification of field types introduced in
  version 1.4.0. Earlier versions worked as expected, if only accidentally,
  since the time zone is ignored when a string is converted to a
  timestamp. While this change makes timestamp more usable again for
  storing UTC time stamps, I strongly recommend using timestamp with time zone since it's interpretation is unambiguous. The API reference is now
  updated with details about how the ptime OCaml type is mapped for
  different database systems.
• Drop specification of OCaml string as SQL text for PostgreSQL. This is
  due to issues with implicit conversions and function overloading when the
  desired type on the SQL side is char, varchar, or jsonb.
• Add Caqti_type.redact to protect sensitive information from being
  logged.
• Only log parameters if $CAQTI_DEBUG_PARAM is set to "true".
• When logging requests, show underlying values for custom types.
• Reject multi-row response in find_opt implementation for sqlite3.
• Tolerate Lwt promise rejections in Pool.use.