Revert "fix atached_file assertion"

This reverts commit 3b25a78.

Author: FynnBe

tests/build_spec/test_build_spec.py

@@ -1,5 +1,3 @@
-from pathlib import Path
-
 import bioimageio.spec as spec
 from bioimageio.core import load_raw_resource_description, load_resource_description
 from bioimageio.core.resource_io import nodes
@@ -95,7 +93,7 @@ def _test_build_spec(
     attachments = loaded_model.attachments or {}
     if "files" in attachments:
         for attached_file in attachments["files"]:
-            assert Path(attached_file).exists()
+            assert attached_file.exists()
 
 
 def test_build_spec_pytorch(any_torch_model, tmp_path):