for the AnswerCorrectness class.

_factual_correctness, which is a
weighted harmonic mean of precision and recall,
where the recall is weighted by a factor of beta.
The F-beta score is defined as:
F-beta = (1 + beta^2) * (precision * recall) / (beta^2 * precision + recall)
The F-beta score is a generalization of the F1 score,
where beta = 1.0. The F1 score is the harmonic mean of
precision and recall, and is defined as:
F1 = 2 * (precision * recall) / (precision + recall)

calculation in factual correctness and keeping
the f1 score as f1-beta score as requested.