only ignoring type comment for Python version 3.6

https://mypy.readthedocs.io/en/stable/common_issues.html#python-version-and-system-platform-checks

Author: PatMyron

src/cloudformation_cli_python_lib/recast.py

@@ -1,3 +1,4 @@
+import sys
 import typing
 from typing import Any, Dict, List, Mapping, Set
 
@@ -127,5 +128,8 @@ def get_forward_ref_type() -> Any:
     # introspection is valid:
     # https://docs.python.org/3/library/typing.html#typing.ForwardRef
     if "ForwardRef" in dir(typing):
-        return typing.ForwardRef  # type: ignore
+        if sys.version_info > (3, 6):
+            return typing.ForwardRef
+        else:
+            return typing.ForwardRef  # type: ignore
     return typing._ForwardRef  # type: ignore