Allow to parse TimeZoneOffset with ±[hh] only

[antonkomarev]

@BenMorel I found that it's pretty difficult to parse Postgres TIMESTAMP WITH TIMEZONE column value using this library. Because PG omits :[mm] part if they are :00 in offset. Because of it we need to analyse response from database of each timestamp field and append :00 suffix on the end (if it's missing).

ISO 8601 allows to omit minutes. Let's support TimeZoneOffset with ±[hh] only.

The UTC offset is appended directly to the time instead of "Z" suffix above; other nautical time zone letters are not used. The offset is applied to UTC to get the civil time in the designated time zone in the format '±[hh]:[mm]', '±[hh][mm]', or '±[hh]'.

INSERT INTO test (ts_with_tz) VALUES ('2024-01-01 09:00:00Z');

SET TIME ZONE 'UTC';
SELECT ts_with_tz FROM test;
-- 2024-01-01 09:00:00+00

SET TIME ZONE INTERVAL '+03:00';
SELECT ts_with_tz FROM test;
-- 2024-01-01 12:00:00+03

SET TIME ZONE INTERVAL '+03:01';
SELECT ts_with_tz FROM test;
-- 2024-01-01 12:01:00+03:01

Note: Many IDEs and DB tools appends :00 omitted seconds suffix before the output, so it's visible only in raw DB responses.

[BenMorel]

Makes sense. Thank you, @antonkomarev!

[BenMorel]

Released as 0.8.1.