Python 3.12 status and blockers

[SimonHeybrock]

Status of 3.12 support

pip -> done in #3321

• Building wheels works with conan==1.62. Note that this is not released yet (2023-11-09), but we can install from the develop branch. This has been released now. See Add Python 3.12 for PyPI #3321
• Numba does not support 3.12 yet, this is an optional dependency. If we avoid installing it in the wheel tests those will be skipped.
• h5py does not support 3.12 yet, this is an optional Scipp dependency, but our tests are currently not configured to be skipped. has been released now.

conda

• On conda-forge, there latest conan is 1.59, i.e., there will likely never be a 1.62 version.
• We would need to move to conan 2. This is currently blocked by cmake-conan not fully supporting it. There is a develop2 branch which we could try.
• conda-forge-pinning supports only up to 3.11. We could make packages without pinning, but the setup would become more complicated.

[jl-wynen]

conda-forge-pinning supports only up to 3.11. We could make packages without pinning, but the setup would become more complicated.

There is a way to add 3.12 to the pinning: #3353
This isn't ideal but it should not cause any problems. The 3.12 packages would be incompatible with the pinning but can be installed along with other compatible packages.

[SimonHeybrock]

cmake-conan now describes experimental Conan 2 support: https://github.com/conan-io/cmake-conan.