Add Post.accessibility_caption property

instaloader/structures.py

@@ -397,6 +397,16 @@ class Post:
             return (pcaption[:30] + u"\u2026") if len(pcaption) > 31 else pcaption
         return _elliptify(self.caption) if self.caption else ''
 
+    @property
+    def accessibility_caption(self) -> Optional[str]:
+        """Accessibility caption of the post, if available.
+
+        .. versionadded:: 4.9"""
+        try:
+            return self._field("accessibility_caption")
+        except KeyError:
+            return None
+
     @property
     def tagged_users(self) -> List[str]:
         """List of all lowercased users that are tagged in the Post."""