refactor: Interpreterのdefineメソッドを同期関数に

[takejohn]

What

軽微なリファクタリングです。
Interpreterのdefineメソッドを削除し、defineSyncメソッドの名前をdefineに変更します。

Why

もともとのdefineメソッドは効果のないasync/awaitを使用していました。

Additional info (optional)

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/interpreter/index.ts	85.71%	1 Missing ⚠️
❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Files with missing lines	Coverage Δ
src/interpreter/index.ts	71.87% <85.71%> (-13.94%)	⬇️

... and 29 files with indirect coverage changes

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[syuilo]

🙏🏻