docs(boxsdk): Add deprecation notice for client module in legacy SDK (#1116)

Author: Hawra2020

boxsdk/client/client.py

@@ -83,6 +83,12 @@ def __init__(self, oauth: 'OAuth2', session: Session = None):
             The session object to use. If None is provided then an instance of :class:`AuthorizedSession` will be used.
         """
         super().__init__()
+        warn(
+            "The 'Client' class and the entire 'boxsdk' package is deprecated and will be removed in the future version. "
+            "It is recommended to use 'box_sdk_gen' package and 'BoxClient' instead. ",
+            DeprecationWarning,
+            stacklevel=2,
+        )
         self._oauth = oauth
         if session is not None:
             self._session = session

setup.py

@@ -7,7 +7,7 @@
 from setuptools.command.test import test as TestCommand
 
 CLASSIFIERS = [
-    'Development Status :: 6 - Mature',
+    'Development Status :: 5 - Production/Stable',
     'Intended Audience :: Developers',
     'License :: OSI Approved :: Apache Software License',
     'Programming Language :: Python',