fix: nullable

[ye11ow]

create stream hello(nstr nullable(string), str string, nint nullable(uint64), int uint64, nbool nullable(bool), bool bool, ndate nullable(datetime(3)), date datetime(3))
insert INTO hello(nstr, str, nint, int, nbool, bool, ndate, date) VALUES('test_nstr', 'test2_str', 123, 456, false, true, now(), now())
insert INTO hello(nstr, str, nint, int, nbool, bool, ndate, date) VALUES(null, 'test2_str', null, 456, null, true, null, now())

Closes #4
Closes #22

[jovezhong]

Thanks for the fix. Can you also bump up the version in the PR and update PR. I can also merge this PR then have that in another commit.

[ye11ow]

Thanks for the fix. Can you also bump up the version in the PR and update PR. I can also merge this PR then have that in another commit.

bumped to 2.1.3