[Python-modules-team] Bug#975731: package breaks with python3.9

[VA]

Package: python3-asttokens
Version: 2.0.3-1

Since Debian upgraded to Python 3.9, asttokens is mostly broken, for 
example this program fails:

     from asttokens import ASTTokens

     src = """
     from x import Foo
     class C:
         def __init__(self):
             self.foo = Foo(a=1)
     """

     astt = ASTTokens(src, parse=True)

It works with:
- Python 3.8 and asttokens 2.0.3
- Python 3.9 and asttokens 2.0.4

But not with Python 3.9 and asttokens 2.0.3.
See https://github.com/gristlabs/asttokens/pull/56

Please update asttokens for Python 3.9.