Revert "Fix type errors after adding types to the py dependency"

This reverts commit 930a158a6a.

Regression test from Bruno Oliveira.

src/_pytest/nodes.py

@@ -462,7 +462,6 @@ class Item(Node):
     @cached_property
     def location(self) -> Tuple[str, Optional[int], str]:
         location = self.reportinfo()
-        assert isinstance(location[0], py.path.local), location[0]
         fspath = self.session._node_location_to_relpath(location[0])
         assert type(location[2]) is str
         return (fspath, location[1], location[2])