Fix lint in Makefile, fix mypy

Author: asmith26

Makefile

@@ -16,7 +16,7 @@ fix-lint:
 	isort --lines 120 --recursive --use-parentheses pandas_toolkit setup.py
 
 lint:
-	tox lint
+	tox -e lint
 
 test-all: clean-test
 	tox

setup.py

@@ -2,7 +2,7 @@
 
 from setuptools import setup
 
-import pandas_toolkit
+from pandas_toolkit import __version__  # type: ignore
 
 _here = os.path.abspath(os.path.dirname(__file__))
 
@@ -11,7 +11,7 @@
 
 setup(
     name="pandas_toolkit",
-    version=pandas_toolkit.__version__,
+    version=__version__,
     description="A collection of pandas accessors to help with common machine learning related functionality.",
     long_description=long_description,
     long_description_content_type="text/markdown",