Make the setup.cfg match the rest of the repo's license. (#3335)

Author: jack-edmonds-dd

setup.cfg

@@ -1,5 +1,5 @@
 # Unless explicitly stated otherwise all files in this repository are licensed
-# under the 3-clause BSD style license (see LICENSE).
+# under the Apache-2.0 License (see LICENSE).
 # This product includes software developed at Datadog (https://www.datadoghq.com/).
 # Copyright 2019 Datadog, Inc.
 
@@ -17,11 +17,11 @@ keywords =
 author = Datadog, Inc.
 author_email = packages@datadoghq.com
 url = https://github.com/DataDog/datadog-api-client-python
-license = BSD
+license = Apache-2.0
 platforms = any
 classifiers=
     Intended Audience :: Developers
-    License :: OSI Approved :: BSD License
+    License :: OSI Approved :: Apache Software License
     Operating System :: OS Independent
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9