Update gt4py: np.bool_ external and gtscript round()

[romanc]

Description

This PR updates the GT4Py submodule fixing a bug with np.bool_ types when used as externals (missing support for that type in the ValueInliner). We now also expose round() and round_away_from_zero() in gtscript.

Fixes #203

How Has This Been Tested?

New tests in GT4Py.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas: N/A
• I have made corresponding changes to the documentation: N/A
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• New check tests, if applicable, are included: N/A

[romanc]

@oelbert feel free to hit that merge button if you approve.

[twicki]

Looks good, thanks!