fix: `voicevox_user_dict_add_word`がスタックを破壊するのを修正 #2424

Job	Run time
config	1s
build_and_deploy (windows-2019, directml, x86_64-pc-windows-msvc, windows-x64-directml, directml)	9m 39s
deploy_model	9s
build_and_deploy (ubuntu-20.04, cuda, x86_64-unknown-linux-gnu, linux-x64-gpu, cuda)	3m 54s
build_and_deploy (macos-11, aarch64-apple-darwin, osx-arm64-cpu, cpu)	7m 58s
build_java_package	0s
download_test	0s
build_xcframework	0s
	21m 41s

Provide feedback