Update config to allow running mypy on Captum in fbcode (pytorch#1386)

Summary:
Pull Request resolved: pytorch#1386

Running mypy directly on Captum within fbcode results in errors due to fb only directories, which doesn't match the behavior of mypy in OSS.

Add appropriate excludes to setup.cfg to enable direct usage of mypy in fbcode

Reviewed By: craymichael

Differential Revision: D64576023

fbshipit-source-id: 59df78ea24719c9eba307836c5fe2373541cd800

setup.cfg

@@ -11,3 +11,9 @@ exclude =
 omit =
     test/*
     setup.py
+
+[mypy]
+exclude = ^.*fb.*$
+
+[mypy-captum.log.fb.*]
+ignore_errors = True