fixing save checkpoint for best metric (#1694)

* fixing save checkpoint for  best metric

* fixing save checkpoint for  best metric v2

* Update mmcv/runner/hooks/evaluation.py
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

* update for lint error

* fixing lint error

* fix lint
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

mmcv/runner/hooks/evaluation.py

@@ -344,7 +344,9 @@ class EvalHook(Hook):
             runner.meta['hook_msgs']['best_ckpt'] = self.best_ckpt_path
 
             runner.save_checkpoint(
-                self.out_dir, best_ckpt_name, create_symlink=False)
+                self.out_dir,
+                filename_tmpl=best_ckpt_name,
+                create_symlink=False)
             runner.logger.info(
                 f'Now best checkpoint is saved as {best_ckpt_name}.')
             runner.logger.info(