[16Beta1][doc] pgstat: Track time of the last scan of a relation

Hi, hackers.
 PostgreSQL 16 Beta1, added last access time to pg_stat_all_tables and pg_stat_all_indexes views by this patch [1].
According to the documentation [2], the data type of the columns added to these views is 'timestamptz'.
However, columns of the same data type in pg_stat_all_tables.last_vacuum, last_analyze and other tables are unified to
'timestampwith time zone'. The attached patch changes the data type of the added column from timestamptz to timestamp
withtime zone. 

[1] pgstat: Track time of the last scan of a relation
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=c037471832e1ec3327f81eebbd8892e5c1042fe0
[2] pg_stat_activity view
https://www.postgresql.org/docs/16/monitoring-stats.html#MONITORING-PG-STAT-ALL-TABLES-VIEW

Regards,
Noriyoshi Shinoda