fix: remove em dash from module docstring

Author: mesutoezdil

src/agentevals/openai_eval_backend.py

@@ -1,9 +1,4 @@
-"""OpenAI Evals API backend — delegates grading to the OpenAI Evals API.
-
-Builds testing criteria from the evaluator config, submits invocation pairs
-as JSONL items, polls for completion, and maps per-item results back to a
-MetricResult.
-"""
+"""OpenAI Evals API backend."""
 
 from __future__ import annotations