bpo-38605: Revert making 'from __future__ import annotations' the default (GH-25490)

This reverts commits 044a1048ca and 1be456ae9d, adapting the code to changes that happened after it.

Tools/peg_generator/pegen/python_generator.py

@@ -27,7 +27,7 @@
 # @generated by pegen from {filename}
 
 import ast
-from typing import Optional
+from typing import Optional, Any
 
 from pegen.parser import memoize, memoize_left_rec, logger, Parser