fix: error when precision_score return float

When precision_score returns float, score.size will throw an error `AttributeError: 'float' object has no attribute 'size'`

precision.py

@@ -142,4 +142,4 @@ class Precision(evaluate.Metric):
             sample_weight=sample_weight,
             zero_division=zero_division,
         )
-        return {"precision": float(score) if score.size == 1 else score}
+        return {"precision": score if isinstance(score, float) else float(score)}