Updated Polyscript & Coincident to their latest

[WebReflection]

Description

This MR is a follow up of this one: pyscript/polyscript#132

It's meant to test improvements (or possible issues) in CI or in the wild, using the latest single rountrip and simplified coincident approach.

Changes

• updated polyscript to its "beta" version
• tested everything is fine

Checklist

• I have checked make build works locally.
• I have created / updated documentation for this change (if applicable).

[WebReflection]

this put a big smile on my face, it's usually 3 up to 5 but on average I've seen 30 seconds less time, compared to other normal builds ... meaning there is some gain.

Locally, it used to take ~32 seconds and now is more like ~19 for the pyodide in worker case ... and like I've said, there's more to do but as a starter, and a fundamental change in the deepest part of our core, I hope this improvement is welcomed.