Drop redundant return type hint

__init__() methods don't need a return type hint unless they take no
arguments.

Signed-off-by: Benjamin Gilbert <[email protected]>

Author: bgilbert

openslide/__init__.py

@@ -189,7 +189,7 @@ class OpenSlide(AbstractSlide):
     operations on the OpenSlide object, other than close(), will fail.
     """
 
-    def __init__(self, filename: str | Path) -> None:
+    def __init__(self, filename: str | Path):
         """Open a whole-slide image."""
         AbstractSlide.__init__(self)
         self._filename = filename