don't allow unicode into type_map on Windows (closes #21652)

Patch from Vladimir Iofik.
diff --git a/Misc/NEWS b/Misc/NEWS
index 4f86a51..982bf30 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -35,6 +35,9 @@
 Library
 -------
 
+- Issue #21652: Prevent mimetypes.type_map from containing unicode keys on
+  Windows.
+
 - Issue #21729: Used the "with" statement in the dbm.dumb module to ensure
   files closing.