fix typing tests with 3.6

tests/test_typing.py

@@ -1,6 +1,6 @@
 import sys
 from collections import namedtuple
-from typing import Any, Callable as TypingCallable, Dict, ForwardRef, List, NamedTuple, NewType, Union  # noqa: F401
+from typing import Any, Callable as TypingCallable, Dict, List, NamedTuple, NewType, Union  # noqa: F401
 
 import pytest
 from typing_extensions import Annotated  # noqa: F401
@@ -24,6 +24,12 @@
 except ImportError:
     mypy_extensions_TypedDict = None
 
+try:
+    from typing import ForwardRef
+except ImportError:
+    # ForwardRef is only available in Python 3.6+
+    pass
+
 ALL_TYPEDDICT_KINDS = (typing_TypedDict, typing_extensions_TypedDict, mypy_extensions_TypedDict)