Small bug when running local inference

[billlyzhaoyh]

When I try to run the local classifier without making an LLM called the following line results in an error:

https://github.com/tryolabs/restricttotopic/blob/main/validator/main.py#L360
TypeError: unsupported operand type(s) for +: 'set' and 'set'

Which I believe is a simple fix from

candidate_topics = model_input["valid_topics"] +  model_input["invalid_topics"]

to

candidate_topics = list(model_input["valid_topics"]) + list(model_input["invalid_topics"])

happy to raise a PR to help out