fixed Image.mode for Pillow 10.1+ (#122)

Signed-off-by: Alexander Piskun <bigcat88@icloud.com>

CHANGELOG.md

@@ -7,6 +7,7 @@ All notable changes to this project will be documented in this file.
 - `Python 3.12`, `PyPy 3.10` wheels.
 - `Depth Image` read support, they are available as a list in `im.info["depth_images"]` #116
 - `options.SAVE_NCLX_PROFILE` - default `False` to be full compatible with previous versions, but in next versions may be changed to `True`. #118 Thanks to @wiggin15
+- Support for `Pillow 10.1.0`
 
 ### Changed
 

pillow_heif/as_plugin.py

@@ -36,6 +36,7 @@ class _LibHeifImageFile(ImageFile.ImageFile):
 
     _heif_file: Union[HeifFile, None] = None
     _close_exclusive_fp_after_loading = True
+    _mode: str  # only for Pillow 10.1+
 
     def __init__(self, *args, **kwargs):
         self.__frame = 0
@@ -127,7 +128,11 @@ def _seek_check(self, frame):
     def _init_from_heif_file(self, img_index: int) -> None:
         if self._heif_file:
             self._size = self._heif_file[img_index].size
-            self.mode = self._heif_file[img_index].mode
+            if pil_version[:4] not in ("9.1.", "9.2.", "9.3.", "9.4.", "9.5.", "10.0"):
+                # starting from Pillow 10.1, `mode` is a readonly property.
+                self._mode = self._heif_file[img_index].mode
+            else:
+                self.mode = self._heif_file[img_index].mode
             self.info = self._heif_file[img_index].info
             self.info["original_orientation"] = set_orientation(self.info)