Limit PEP 604 test by Python 3.10

tests/decorators/test_python.py

@@ -109,7 +109,10 @@ def t1() -> TypeDictClass:
 
         assert t1().operator.multiple_outputs is True
 
-    def test_infer_multiple_outputs_union_type(self):
+    # We do not enable `from __future__ import annotations` for particular this test module,
+    # that mean `str | None` annotation would raise TypeError in Python 3.9 and below
+    @pytest.mark.skipif(sys.version_info < (3, 10), reason="PEP 604 is implemented in Python 3.10")
+    def test_infer_multiple_outputs_pep_604_union_type(self):
         @task_decorator
         def t1() -> str | None:
             # Before PEP 604 which are implemented in Python 3.10 `str | None`
@@ -120,6 +123,13 @@ def t1() -> str | None:
 
         assert t1().operator.multiple_outputs is False
 
+    def test_infer_multiple_outputs_union_type(self):
+        @task_decorator
+        def t1() -> Union[str, None]:
+            return "foo"
+
+        assert t1().operator.multiple_outputs is False
+
     def test_infer_multiple_outputs_forward_annotation(self):
         if TYPE_CHECKING: