set cpp project dir in CI, part 2

.github/workflows/cmake-multi-platform.yml

@@ -58,12 +58,11 @@ jobs:
       # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
       # See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type
       run: >
-        cd cpp
         cmake -B ${{ steps.strings.outputs.build-output-dir }}
         -DCMAKE_CXX_COMPILER=${{ matrix.cpp_compiler }}
         -DCMAKE_C_COMPILER=${{ matrix.c_compiler }}
         -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
-        -S ${{ github.workspace }}
+        -S ${{ github.workspace }}/cpp
 
     - name: Build
       # Build your program with the given configuration. Note that --config is needed because the default Windows generator is a multi-config generator (Visual Studio generator).