Changes from Python 3.6 to Python 3.7

--- /home/docs/checkouts/readthedocs.org/user_builds/restrictedpython/checkouts/latest/docs/contributing/ast/python3_6.ast
+++ /home/docs/checkouts/readthedocs.org/user_builds/restrictedpython/checkouts/latest/docs/contributing/ast/python3_7.ast
@@ -1,11 +1,11 @@
--- Python 3.6 AST
+-- Python 3.7 AST
 -- ASDL's 7 builtin types are:
 -- identifier, int, string, bytes, object, singleton, constant
 --
 -- singleton: None, True or False
 -- constant can be None, whereas None means "no value" for object.
 
-module Python version "3.6"
+module Python version "3.7"
 {
     mod = Module(stmt* body)
         | Interactive(stmt* body)