Unneeded sources in `src/daemon/backend/data/CMakeLists.txt`

The following sources don't need to be included as dependencies of the storage target defined in src/daemon/backend/data/CMakeLists.txt:

target_sources(storage
    PUBLIC
    ${INCLUDE_DIR}/daemon/backend/data/chunk_storage.hpp
    PRIVATE
    ${INCLUDE_DIR}/common/path_util.hpp
    ${INCLUDE_DIR}/common/common_defs.hpp
    ${INCLUDE_DIR}/daemon/backend/data/data_module.hpp     <===
    ${INCLUDE_DIR}/daemon/backend/data/file_handle.hpp
    ${CMAKE_CURRENT_LIST_DIR}/chunk_storage.cpp
    ${CMAKE_CURRENT_LIST_DIR}/data_module.cpp              <===
    )

The reason is that the same CMake script already defines the data_module target which includes those sources and storage has a direct dependency on it via target_link_libraries(storage ... data_module).