build: set es2020 as target in tsup.config.ts

This change adds ES2020 as the compilation target for the
unplugin-typia package, ensuring modern JavaScript features are
properly supported while maintaining compatibility.

Author: ryoppippi

packages/unplugin-typia/tsup.config.ts

@@ -7,6 +7,7 @@ export default <Options>{
 	],
 	clean: true,
 	format: ['esm'],
+	target: 'es2020',
 	dts: true,
 	cjsInterop: true,
 	splitting: true,