[BUG] incorrect type hints such as `callable`

## Describe the bug

Reading the code, it's clear this code base can really benefit from type checking, running vanilla `mypy` reveals over 1.2k type errors.

For example, `callable` is not a valid type hint: https://github.com/huggingface/lighteval/blob/v0.9.2/src/lighteval/metrics/utils/metric_utils.py#L62-L63

## To Reproduce

```bash
uv sync --extra dev
uv pip install mypy==0.15.0
mypy src
```

## Expected behavior

Type hints to be correct.

## Version info

`lighteval==0.9.2`