`Synthesizer::new`を非asyncにする #2239

Job	Run time
actionlint	20s
actionlint	20s
shellcheck	16s
shellcheck	16s
build-and-test-java-api (windows-latest)	8m 54s
build-and-test-java-api (windows-latest)	8m 54s
build-and-test-python-api (windows-latest)	11m 57s
build-and-test-python-api (windows-latest)	11m 57s
build-and-test-java-api (macos-latest)	4m 28s
build-and-test-java-api (macos-latest)	4m 28s
build-and-test-python-api (macos-latest)	9m 42s
build-and-test-python-api (macos-latest)	9m 42s
build-and-test-java-api (ubuntu-latest)	5m 34s
build-and-test-java-api (ubuntu-latest)	5m 34s
build-and-test-python-api (ubuntu-latest)	3m 49s
build-and-test-python-api (ubuntu-latest)	3m 49s
build-unix-cpp-example (macos-latest, osx-x64-cpu-cpp-shared)	4m 4s
build-unix-cpp-example (macos-latest, osx-x64-cpu-cpp-shared)	4m 4s
build-windows-cpp-example	8m 22s
build-windows-cpp-example	8m 22s
build-unix-cpp-example (ubuntu-latest, linux-x64-cpu-cpp-shared)	2m 50s
build-unix-cpp-example (ubuntu-latest, linux-x64-cpu-cpp-shared)	2m 50s
c-header	1m 43s
c-header	1m 43s
rust-integration-test-strategy-matrix	7s
rust-integration-test-strategy-matrix	7s
rust-lint	2m 16s
rust-lint	2m 16s
rust-unit-test	5m 58s
rust-unit-test	5m 58s
validate-cargo-lock	27s
validate-cargo-lock	27s
rust-integration-test (windows-2019, directml)	4m 41s
rust-integration-test (windows-2019, directml)	30s
rust-integration-test (macos-11)	2m 23s
rust-integration-test (macos-11)	2m 23s
rust-integration-test (ubuntu-20.04)	1m 35s
rust-integration-test (ubuntu-20.04)	1m 35s
	2h 34m 41s

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