fix(bench): incorrect opening method in @napi-rs/simple-git repository (#120)

Author: other-yuka

benchmarks/index.bench.ts

@@ -21,7 +21,7 @@ describe('open', () => {
   });
 
   bench('@napi-rs/simple-git', () => {
-    SimpleGitRepository.init(gitDir);
+    new SimpleGitRepository(gitDir);
   });
 });