Update action.yml

Author: mcbarton

.github/actions/Build_and_Test_cppyy/action.yml

@@ -152,7 +152,7 @@ runs:
         cd ..\cppyy-backend\build\
         # Build and Install cppyy-backend
         $env:INCLUDE=$env:CPLUS_INCLUDE_PATH
-        cmake -DCppInterOp_DIR=$env:CPPINTEROP_DIR ..
+        cmake -DCppInterOp_DIR=$env:CPPINTEROP_DIR -DCMAKE_INCLUDE_PATH="$env:CPLUS_INCLUDE_PATH" ..
         cmake --build . --parallel ${{ env.ncpus }}
         cp libcppyy-backend.lib $env:CPPINTEROP_DIR\lib\
         cd ..