fix!: Pythonの`Synthesizer.metas`と`UserDict.words`を非ゲッターに #3037

Job	Run time
config	1s
deploy_model	14s
build_and_deploy (windows-2019, x86_64-pc-windows-msvc, windows-x64, plain-cdylib, true)	7m 38s
build_and_deploy (ubuntu-20.04, x86_64-unknown-linux-gnu, linux-x64, plain-cdylib, true)	2m 33s
build_and_deploy (macos-13, aarch64-apple-darwin, osx-arm64, plain-cdylib, true)	4m 41s
download_test	0s
build_xcframework	0s
build_java_package	0s
	15m 7s

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