fix: convert token usage values to int before summing

[rajkumar-prog]

Problem

When running evals, the OpenAI API now returns CompletionTokensDetails objects instead of plain integers for token usage values. The current code tries to sum these directly, causing:

TypeError: unsupported operand type(s) for +: 'int' and 'CompletionTokensDetails'

Fixes #1582

Fix

Wrap the value with int() before summing, so it works regardless of whether the API returns a plain integer or a CompletionTokensDetails object.

Change

evals/cli/oaieval.py line 282 — added int() conversion before summing token usage values.