Allow scripts in environement

[BishopWolf]

Description

A clean environment for building my project is not enough, I need to define some variables for cmake. Usually they are in the CIBW_BEFORE_BUILD but they are not passed down to the container environment.
The use of CIBW_ENVIRONMENT is limited to variable declaration, I can't use a script to recreate my build environment. Or am I wrong and just don't know how to do it?

The current builds for linux are failing as we use a container based on manylinux with prebuilt libraries

Build log

https://github.com/OpenGATE/opengate/pull/935/checks

CI config

https://github.com/OpenGATE/opengate/pull/935/changes

Remarks

In these builds, windows and macos wheels are being produced, only linux is failing