StringIO in Python 3

[Ismo Toijala (Huld)]

The import of StringIO in

langkit/langkit/templates/python_api/module_py.mako

Line 1274 in a33c022

 import StringIO 

does not work in Python 3.

It should be from io import StringIO.

[Pierre-Marie de Rodat]

Hello,

You are right, thank you for reporting this. We have a candidate fix for this issue: #354 and this issue will automatically be closed when this PR is merged.