Update upper Python version to Python 3.12

[sandcha]

Hi there!

I really enjoy OpenFisca, but I recently encountered an issue.

Here is what I have seen:

openfisca-core current compatible Python versions are: 3.9, 3.10 and 3.11

Now, these revisions are classified as security by Python which means:
"only security fixes are accepted and no more binaries are released, but new source-only versions can be released"

Then on new OS revision like Ubuntu LTS, the default Python version is 3.12 as said in #1226.

Here is what I expected to happen:

I expected openfisca to be on the latest really alive Python version 😅, Python 3.12 or a more recent revision (3.13 for example?).

Here is what actually happened:

We didn't update the Python version yet and people start to manage installation issues (#1226 and unlisted issues 😢).

Additional information?

Our current lower revision for numpy (1.24.2) might not be compatible with Python 3.12.

Context

I identify more as a:

• Analyst (I make macroscopic computations on real populations).
• Developer (I create tools that use the existing OpenFisca code).