ci.eval.compare: keep warnings as warnings rather than raising them as errors

This reverts commit f8210561f3 (ci.eval.compare: turn warnings into errors, 2025-09-16).

It turns out that there are normal math warnings and we don't want to block CI on the math coming out wrong.

ci/eval/compare/cmp-stats.py

@@ -3,7 +3,6 @@ import json
 import numpy as np
 import os
 import pandas as pd
-import warnings
 
 from dataclasses import asdict, dataclass
 from pathlib import Path
@@ -304,9 +303,6 @@ def main():
 
     options = parser.parse_args()
 
-    # Turn warnings into errors
-    warnings.simplefilter("error")
-
     before_stats = Path(options.before)
     after_stats = Path(options.after)