Find module name in an OS-agnostic fashion (#24526)

* Find module name in an OS-agnostic fashion

* address review comment

src/transformers/dynamic_module_utils.py

@@ -234,7 +234,7 @@ def get_cached_module_file(
     pretrained_model_name_or_path = str(pretrained_model_name_or_path)
     is_local = os.path.isdir(pretrained_model_name_or_path)
     if is_local:
-        submodule = pretrained_model_name_or_path.split(os.path.sep)[-1]
+        submodule = os.path.basename(pretrained_model_name_or_path)
     else:
         submodule = pretrained_model_name_or_path.replace("/", os.path.sep)
         cached_module = try_to_load_from_cache(
@@ -271,7 +271,7 @@ def get_cached_module_file(
     full_submodule = TRANSFORMERS_DYNAMIC_MODULE_NAME + os.path.sep + submodule
     create_dynamic_module(full_submodule)
     submodule_path = Path(HF_MODULES_CACHE) / full_submodule
-    if submodule == pretrained_model_name_or_path.split(os.path.sep)[-1]:
+    if submodule == os.path.basename(pretrained_model_name_or_path):
         # We copy local files to avoid putting too many folders in sys.path. This copy is done when the file is new or
         # has changed since last copy.
         if not (submodule_path / module_file).exists() or not filecmp.cmp(