Fix Python package build on Windows with setuptools >= 65.4.0

For some reason, setuptools thinks it needs to be able to find the user's
home directory to build a wheel, but on Windows this relies on an environment
variable (USERPROFILE) that we weren't by default passing in through SCons.

.github/workflows/main.yml

@@ -495,7 +495,7 @@ jobs:
         shell: bash
       - name: Build Cantera
         run: scons build -j2 boost_inc_dir=%BOOST_ROOT% debug=n logging=debug
-          python_package=full env_vars=PYTHONPATH,GITHUB_ACTIONS
+          python_package=full env_vars=USERPROFILE,GITHUB_ACTIONS
           msvc_version=${{ matrix.vs-toolset }} f90_interface=n --debug=time
         shell: cmd
       - name: Test Cantera