Fix excluding files properly (#345)

Author: jillingk

setup.py

@@ -2,7 +2,7 @@
 
 setup(
     name='Adyen',
-    packages=find_packages(include="Adyen*", exclude=["tests", "tests.*"]),
+    packages=find_packages(include=["Adyen*"], exclude=["tests", "tests.*"]),
     version='12.8.0',
     maintainer='Adyen',
     maintainer_email='support@adyen.com',