[libre-riscv-dev] mypy type annotations for nmigen

[Jacob Lifshay]

I created some type annotations for nmigen:
https://salsa.debian.org/Kazan-team/simple-barrel-processor/tree/master/mypy_stubs/nmigen

to use, add mypy.ini and mypy_stubs to repo root and run mypy or use pyls
(python language server) with pyls-mypy

If we're going to use this much, we should put the nmigen type annotations
in a separate repo so it's easier to update across all users.

Jacob