Update category_models: fix warning

src/long_articles/category_models.py

@@ -84,8 +84,8 @@ class CategoryRegressionV1:
                 if not param_name:
                     continue
                 param_index = self.features.index(param_name) + 1
-                param = params[param_index]
-                p_value = p_values[param_index]
+                param = params.iloc[param_index]
+                p_value = p_values.iloc[param_index]
                 if p_value < 0.1:
                     print(f"{row['y']:.3f}\t{row['residual']:.3f}\t{row['category']}\t{param:.2f}\t{row['title']}")
             r_min = residuals.min()