server: replace relative_to check with is_relative_to

Author: pohmelie

Diff for: src/aioftp/server.py

@@ -1033,9 +1033,7 @@ def get_paths(connection, path):
         base_path = connection.user.base_path
         real_path = base_path / str(resolved_virtual_path.relative_to("/"))
         # replace with `is_relative_to` check after 3.9+ requirements lands
-        try:
-            real_path.relative_to(base_path)
-        except ValueError:
+        if not real_path.is_relative_to(base_path):
             real_path = base_path
             resolved_virtual_path = pathlib.PurePosixPath("/")
         return real_path, resolved_virtual_path