remove offset casting

[ChuckHend]

Fixes potential bug that I think would impact situations where sender's locale is not 'utc', but reader's local is.

create table mytest (id integer, ts timestamp with time zone);

insert into mytest values (2, now())

insert into mytest values (3, now() at time zone 'utc')

select * from mytest

 id |              ts               
----+-------------------------------
  2 | 2023-08-10 13:16:40.646644-05  <- correct (this is right now)
  3 | 2023-08-10 18:16:40.652859-05  <- wrong (this is a point in time in the future)