pipeline/python3.8: upgrade astroid to fix KeyError
> File ".../python3.8/site-packages/astroid/__init__.py", line 91, in _inference_tip_cached
> return iter(_cache[func, node])
> KeyError: (<function infer_named_tuple at 0x7f7e0c3fd9d0>, <Call l.1224 at 0x7f7e0af37ca0>)
https://travis-ci.org/fphammerle/free-disk/jobs/630911474