Introduce Python 3.12 image generation

• Introduce with gcc and libffi-dev installed in the meantime
• Use rc tag, unstable Python version

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• Move pre-commit and git installation from 3.11 to 3.12 image.
• Remove gcc and libffi-dev once no longer necessary: Until dulwich, msgpack, rapidfuzz, cffi wheels for Py3.12 are provided to install poetry
• Remove rc tag once Python 3.12 is released as stable

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• Create follow-up ticket for Py 3.13: Introduce 3.13 and drop 3.8 Python image genera... (#10 - closed)