Addressing post-merge comments on #263

[rofinn]

• [X] Merge tests https://github.com/invenia/LibPQ.jl/pull/263#discussion_r1114888240
• [X] Reuse parse(DateTime, x) methods https://github.com/invenia/LibPQ.jl/pull/263#discussion_r1114891344
• [X] Just use TIMESTAMP_FORMAT for UTCDateTime https://github.com/invenia/LibPQ.jl/pull/263#discussion_r1114912125
• [X] Just replace on "+00" rather than regex handling -00, +00:00, etc. https://github.com/invenia/LibPQ.jl/pull/263#discussion_r1114925814

[rofinn]

codecov has gone down because we deleted about 30 LOC.

[rofinn]

Is a patch release fine? We aren't really changing any existing functionality.

[iamed2]

Is a patch release fine? We aren't really changing any existing functionality.

Yup!