correcting Operating System classifier in setup.cfg

Author: shachafl

setup.cfg

@@ -25,7 +25,7 @@ classifier =
     Operating System :: POSIX
     Operating System :: Unix
     Operating System :: MacOS :: MacOS X
-    Operating System :: Windows
+    Operating System :: Microsoft :: Windows
     License :: OSI Approved :: MIT License
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.9