feat: read the finalized dependencies from pixi

[baszalmstra]

With prefix-dev/pixi#4252 the backends now receive the records installed in the host/build environments. This PR adds this information to the recipe to ensure that the SP_DIR and PY_VER variables are set during build.

[ruben-arts]

Works!

 │ │ USING PYTHON_EXECUTABLE=$PREFIX/bin/python
 │ │ USING PKG_CONFIG_EXECUTABLE=$PREFIX/bin/pkg-config
 │ │ Using Python 3.12
 │ │ Using PREFIX: $PREFIX
 │ │ Using SP_DIR: $PREFIX/lib/python3.12/site-packages
 │ │ Using CONDA_BUILD: 1
 │ │ Using CPU_COUNT: 14
 │ │ Using PY_VER: 3.12
 │ │ Using PYTHON: $PREFIX/bin/python
 │ │ Using STDLIB_DIR: 
 │ │ Using ROS_PYTHON_VERSION: 3.12
 │ │ Using SRC_DIR: $SRC_DIR