gh-115882: Reference Unknwn.h for ctypes on Windows (GH-115350)

This allows the module to be compiled with WIN32_LEAN_AND_MEAN enabled

Author: georgthegreat

Misc/NEWS.d/next/Build/2024-02-24-12-50-43.gh-issue-115350.naQA6y.rst

@@ -0,0 +1 @@
+Fix building ctypes module with -DWIN32_LEAN_AND_MEAN defined

Modules/_ctypes/ctypes.h

@@ -32,6 +32,10 @@
 #endif
 #endif
 
+#ifdef MS_WIN32
+#include <Unknwn.h> // for IUnknown interface
+#endif
+
 typedef struct {
     PyTypeObject *DictRemover_Type;
     PyTypeObject *PyCArg_Type;