fix: serialize subtitles for api response

src/program/media/item.py

@@ -265,7 +265,7 @@ def to_extended_dict(self, abbreviated_children=False, with_streams=True):
         dict["file"] = self.file if hasattr(self, "file") else None
         dict["folder"] = self.folder if hasattr(self, "folder") else None
         dict["symlink_path"] = self.symlink_path if hasattr(self, "symlink_path") else None
-        dict["subtitles"] = getattr(self, "subtitles", [])
+        dict["subtitles"] = [subtitle.to_dict() for subtitle in self.subtitles] if hasattr(self, "subtitles") else []
         return dict
 
     def __iter__(self):

src/program/media/subtitle.py

@@ -35,4 +35,12 @@ def remove(self):
         if self.file and Path(self.file).exists():
             Path(self.file).unlink()
         self.file = None
-        return self
+        return self
+
+    def to_dict(self):
+        return {
+            "id": str(self._id),
+            "language": self.language,
+            "file": self.file,
+            "parent_id": self.parent_id
+        }