mypy notes are being discarded

[grota]

In #676 the regexp was modified to include mypy's error codes. That regexp worked for usual output like

a.py:6:5:6:30: error: "type[list[int]]" has no attribute "__origin__"  [attr-defined]

The thing is that if you use a simple reveal_type(1) in your code mypy's output is:

a.py:3:13:3:13: note: Revealed type is "Literal[1]?"

so there is no code, the regex does not match the line which gets discarded.

I took a stab at tweaking the regex, but Lua won this round.