Silence deprecation warning from typed-ast in tests (#7335)

This fixes a deprecation warning about `<>` in Python 2 that came up every
time the full test suite was run.

Author: JukkaL

mypy/fastparse2.py

@@ -15,6 +15,7 @@
 two in a typesafe way.
 """
 import sys
+import warnings
 
 import typing  # for typing.Type, which conflicts with types.Type
 from typing import Tuple, Union, TypeVar, Callable, Sequence, Optional, Any, Dict, cast, List
@@ -106,7 +107,10 @@ def parse(source: Union[str, bytes],
     is_stub_file = fnam.endswith('.pyi')
     try:
         assert options.python_version[0] < 3 and not is_stub_file
-        ast = ast27.parse(source, fnam, 'exec')
+        # Disable deprecation warnings about <>.
+        with warnings.catch_warnings():
+            warnings.filterwarnings("ignore", category=DeprecationWarning)
+            ast = ast27.parse(source, fnam, 'exec')
         tree = ASTConverter(options=options,
                             errors=errors,
                             ).visit(ast)