remove tests for duplicated namespaces

tests/test_namespace.py

@@ -23,21 +23,3 @@ def test_aliases():
                 assert False, obj_name
             assert orig_lib.startswith("arviz"), obj_name
             assert orig_lib != "arviz", obj_name
-
-
-def test_base_alias():
-    import arviz_base
-
-    assert az.base is arviz_base
-
-
-def test_stats_alias():
-    import arviz_stats
-
-    assert az.stats is arviz_stats
-
-
-def test_plots_alias():
-    import arviz_plots
-
-    assert az.plots is arviz_plots