Skip pb files in linters

In isort, black, and flake8, respectively.

Add `format` in Makefile

Run top level packages only

With `setup.py`, to avoid running other unrelated directories.

Refactor

tox.ini

@@ -7,7 +7,7 @@ envlist =
 
 [flake8]
 max-line-length= 100
-exclude=
+exclude=*_pb2*.py
 ignore=
 
 [isort]
@@ -18,6 +18,7 @@ include_trailing_comma=True
 force_grid_wrap=0
 use_parentheses=True
 line_length=88
+skip_glob=*_pb2*.py
 
 [testenv]
 deps =