test: fix coverage reporting (#9148)

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

vitest.config.ts

@@ -15,6 +15,8 @@ export default defineConfig({
 				'**/*.{interface,type,d}.ts',
 				// All index files that *should* only contain exports from other files
 				'**/index.{js,ts}',
+				// All exports files that make subpackages available as submodules
+				'**/exports/*.{js,ts}',
 			],
 		},
 	},