fix(cmake): fix USE_PT_PYTHON_LIBS (deepmodeling#3972)

There was a typo in deepmodeling#3636.

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-->

## Summary by CodeRabbit

- **Refactor**
- Updated build configuration to improve compatibility with PyTorch by
modifying library path settings.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Signed-off-by: Jinzhe Zeng <jinzhe.zeng@rutgers.edu>

source/CMakeLists.txt

@@ -176,10 +176,7 @@ if(BUILD_CPP_IF
         "Cannot determine PyTorch CMake prefix path, error code: $PYTORCH_CMAKE_PREFIX_PATH_RESULT_VAR}, error message: ${PYTORCH_CMAKE_PREFIX_PATH_ERROR_VAR}"
     )
   endif()
-  list(APPEND BACKEND_LIBRARY_PATH ${TensorFlow_LIBRARY_PATH})
-  if(Protobuf_LIBRARY_DIRECTORY)
-    list(APPEND BACKEND_LIBRARY_PATH ${Protobuf_LIBRARY_DIRECTORY})
-  endif()
+  list(APPEND CMAKE_PREFIX_PATH ${PYTORCH_CMAKE_PREFIX_PATH})
 endif()
 if(ENABLE_PYTORCH AND NOT DEEPMD_C_ROOT)
   find_package(Torch REQUIRED)