fix: send isFavorite as boolean in JSON body for Immich 3.x compatibility

[Infineon12]

Problem

After upgrading Immich to 3.x, the integration fails to load favorite images:

Error from API: body={"message":"Validation failed","errors":[{"expected":"boolean","code":"invalid_type","path":["isFavorite"],"message":"Invalid input: expected boolean, received string"}]}

Root Cause

list_favorite_images() in hub.py was sending the request body using data=, which causes aiohttp to serialize all values as strings. Immich 3.x now strictly validates that isFavorite is a boolean.

Fix

• Changed data= to json= so the body is sent as JSON
• Changed the variable name from json to payload to avoid shadowing the built-in module
• Changed "true" (string) to True (boolean)

Fixes #30

[Matikitorch]

Can this please be merged? I believe the integration is completely broken with the latest Immich.

[Infineon12]

So I think I can't do anything, needs to be done by a maintainer.
But at least I can tell you that my gallery is working without any issues with this change.