[CI] Fix ray datasets example and tests, update cutting edge test (#187)

Author: Yard1

xgboost_ray/examples/simple_ray_dataset.py

@@ -19,6 +19,8 @@ def main(cpus_per_actor, num_actors):
     y[bits_to_flip] = 1 - y[bits_to_flip]
 
     data = pd.DataFrame(x)
+    # Ray Datasets require all columns to be string
+    data.columns = [str(c) for c in data.columns]
     data["label"] = y
 
     # There was recent API change - the first clause covers the new

xgboost_ray/tests/test_data_source.py

@@ -443,7 +443,8 @@ class RayDatasetSourceTest(_DistributedDataSourceTest, unittest.TestCase):
     def _testAssignPartitions(self, part_nodes, actor_nodes,
                               expected_actor_parts):
         partitions = [
-            ray.put(pd.DataFrame(p))
+            ray.put(
+                pd.DataFrame(p, columns=[str(x) for x in range(p.shape[1])]))
             for p in np.array_split(self.x, len(part_nodes))
         ]
 

xgboost_ray/tests/test_sklearn.py

@@ -387,10 +387,7 @@ def test_parameter_tuning(self):
         )
         clf.fit(X, y)
         assert clf.best_score_ < 0.7
-        if XGBOOST_VERSION_TUPLE >= (1, 6, 0):
-            assert clf.best_params_ == {"n_estimators": 200, "max_depth": 2}
-        else:
-            assert clf.best_params_ == {"n_estimators": 100, "max_depth": 4}
+        assert clf.best_params_ == {"n_estimators": 100, "max_depth": 4}
 
     def test_regression_with_custom_objective(self):
         self._init_ray()