Make timestamptz return timestamp-aware max / min
Make timestamptz return timestamp-aware max / min

Now timestamptz_recv() uses datetime.datetime.max.replace(tzinfo=utc)
instead of just datetime.datetime.max for 'infinity', and the same for
min.

realazthat/pg8000,kaniini/pg8000,kaniini/pg8000,tlocke/pg8000,realazthat/pg8000