Add Postgre function: `DATE_TRUNC`

[IgnisDa]

PR Info

This PR adds the DATE_TRUNC functions along with docs and tests.

Additional

N/A

[IgnisDa]

@tyt2y3 Could you take a look at this PR? Thanks!

[github-actions[bot]]

:tada: Released In 0.32.2 :tada:

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