Grpc generators: fix Policy CMP0071

cmake_minimum_required(VERSION 3.9)
project(GrpcPreset LANGUAGES CXX)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# cmake_policy(SET CMP0071 NEW)
find_package(Qt6 REQUIRED COMPONENTS Grpc)
qt_standard_project_setup()

qt_add_executable(qtclient src/qtclient.cpp)

qt_add_protobuf(qtclient
    PROTO_FILES ${proto_file}
    PROTO_INCLUDES ${proto_imp}
    OUTPUT_DIRECTORY "${proto_out}/qt"
)

qt_add_grpc(qtclient CLIENT
    PROTO_FILES ${proto_file}
    PROTO_INCLUDES ${proto_imp}
    OUTPUT_DIRECTORY "${proto_out}/qt"
)

target_link_libraries(qtclient PRIVATE Qt6::Grpc)
target_include_directories(qtclient
    PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>"
)