Initial Python v3.12 support

Once first beta is released (22nd May 2023), we can introduce Python v3.12 support, to see how it goes:

• Introduce Python 3.12 image generation (docker/python3/poetry#8 - closed)
  • With gcc and libffi-dev
• Set up v3.12 test job
  • Allow the job to fail with allow_failure: true. It shouldn’t block the pipeline
    • We currently have an issue with rpds-py which does not provide Py3.12 wheel. Package introduced with jsonschema v4.18.0

├── jsonschema ^4.17.3
│   ├── attrs >=22.2.0 
│   ├── importlib-resources >=1.4.0 
│   │   └── zipp >=3.1.0 
│   ├── jsonschema-specifications >=2023.03.6 
│   │   ├── importlib-resources >=1.4.0 (circular dependency aborted here)
│   │   └── referencing >=0.28.0 
│   │       ├── attrs >=22.2.0 (circular dependency aborted here)
│   │       └── rpds-py >=0.7.0 
│   ├── pkgutil-resolve-name >=1.3.10 
│   ├── referencing >=0.28.4 (circular dependency aborted here)
│   └── rpds-py >=0.7.1 (circular dependency aborted here)