[ dergigi/boris ] fix: remove isMounted from useEffect dependencies

- isMounted is a stable function from useMountedState and shouldn't be in deps

- Including it was preventing effects from running correctly

- Fixes issue where articles wouldn't load (stuck on spinner)

https://github.com/dergigi/boris/commit/b117b1e6cfd7f8fb59e949277d0e52201adece59