ImageFile context manager value is typed in Pillow >= 12.1.0

Signed-off-by: Benjamin Gilbert <bgilbert@cs.cmu.edu>

Author: bgilbert

.pre-commit-config.yaml

@@ -58,7 +58,7 @@ repos:
     hooks:
       - id: mypy
         name: Check Python types
-        additional_dependencies: [flask, openslide-bin, pillow, types-PyYAML, types-setuptools]
+        additional_dependencies: [flask, openslide-bin, pillow >= 12.1.0, types-PyYAML, types-setuptools]
 
   - repo: https://github.com/rstcheck/rstcheck
     rev: v6.2.5

openslide/__init__.py

@@ -394,9 +394,7 @@ def detect_format(cls, filename: lowlevel.Filename) -> str | None:
         If the file format is not recognized, return None."""
         try:
             with Image.open(filename) as img:
-                # img currently resolves as Any
-                # https://github.com/python-pillow/Pillow/pull/8362
-                return img.format  # type: ignore[no-any-return]
+                return img.format
         except OSError:
             return None