fix: sub-second value parsing accurately

[eitsupi]

Fix #127

[krlmlr]

Thanks for tracking this down! Just curious, what's the rationale of removing parse_time()?

[eitsupi]

what's the rationale of removing parse_time()?

There was no particular intent; I fixed it in the way that parse_time() was rewritten.

As an aside, I think this function is worth exporting in a follow-up PR.

[eitsupi]

@krlmlr Could you check this?

[krlmlr]

Thanks! The check might be prone to floating-point errors, we'll see.

[eitsupi]

Thanks for merging!