Require Python 3.12 or newer; remove outdated workarounds

Author: dimpase

.devcontainer/onCreate-conda.sh

@@ -6,8 +6,8 @@ conda config --env --add channels conda-forge
 conda config --env --set channel_priority strict
 conda update -y --all --override-channels -c conda-forge
 conda install mamba=1 -n base -y
-mamba env create -y --file environment-3.11-linux.yml || mamba env update --file environment-3.11-linux.yml
+mamba env create -y --file environment-3.12-linux.yml || mamba env update --file environment-3.12-linux.yml
 conda init bash
 
 # Build sage
-conda run -n sage-dev pip install --no-build-isolation -v -v -e . --config-settings=build-dir="build/conda-cp311"
+conda run -n sage-dev pip install --no-build-isolation -v -v -e . --config-settings=build-dir="build/conda-cp312"