tests: Fix path issue on annoying operating system

Author: pawamoy

tests/test_handler.py

@@ -4,17 +4,14 @@
 
 import os
 from glob import glob
+from pathlib import Path
 from textwrap import dedent
-from typing import TYPE_CHECKING
 
 import pytest
 from griffe import DocstringSectionExamples, DocstringSectionKind, temporary_visited_module
 
 from mkdocstrings_handlers.python.handler import CollectionError, PythonHandler, get_handler
 
-if TYPE_CHECKING:
-    from pathlib import Path
-
 
 def test_collect_missing_module() -> None:
     """Assert error is raised for missing modules."""
@@ -141,7 +138,7 @@ def test_extension_paths(tmp_path: Path, expect_change: bool, extension: str | d
             assert normalized == str(tmp_path.joinpath(extension))
         elif isinstance(normalized, dict) and isinstance(extension, dict):
             pth, options = next(iter(extension.items()))
-            assert normalized == {str(tmp_path.joinpath(pth)): options}
+            assert normalized == {str(Path(tmp_path, pth)): options}
         else:
             raise ValueError("Normalization must not change extension items type")
     else: