[Meta Schedule][XGBoost] enable custom callback func test with xgboos…

…t>=1.6.0 (#17168)

enable callback func test with xgboost>=1.6.0

tests/python/meta_schedule/test_meta_schedule_cost_model.py

@@ -257,17 +257,6 @@ def test_meta_schedule_xgb_model_reupdate():
     model.predict(TuneContext(), [_dummy_candidate() for i in range(predict_sample_count)])
 
 
-def xgb_version_check():
-
-    # pylint: disable=import-outside-toplevel
-    import xgboost as xgb
-    from packaging import version
-
-    # pylint: enable=import-outside-toplevel
-    return version.parse(xgb.__version__) >= version.parse("1.6.0")
-
-
-@unittest.skipIf(xgb_version_check(), "test not supported for xgboost version after 1.6.0")
 def test_meta_schedule_xgb_model_callback_as_function():
     # pylint: disable=import-outside-toplevel
     from itertools import chain as itertools_chain
@@ -330,14 +319,12 @@ def avg_peak_score(ys_pred: np.ndarray, d_train1: "xgb.DMatrix"):  # type: ignor
             num_boost_round=10000,
             obj=obj,
             callbacks=[
-                partial(
-                    _get_custom_call_back(
-                        early_stopping_rounds=model.early_stopping_rounds,
-                        verbose_eval=model.verbose_eval,
-                        fevals=[rmse, avg_peak_score],
-                        evals=[(d_train.dmatrix, "tr")],
-                        cvfolds=None,
-                    )
+                _get_custom_call_back(
+                    early_stopping_rounds=model.early_stopping_rounds,
+                    verbose_eval=model.verbose_eval,
+                    fevals=[rmse, avg_peak_score],
+                    evals=[(d_train.dmatrix, "tr")],
+                    cvfolds=None,
                 )
             ],
         )