Issue #8784: Set tarfile default encoding to 'utf-8' on Windows.

Note: file system encoding cannot be None anymore (since r81190, issue #8610).
diff --git a/Misc/NEWS b/Misc/NEWS
index 1335dbc..5a59310 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -421,6 +421,8 @@
 Library
 -------
 
+- Issue #8784: Set tarfile default encoding to 'utf-8' on Windows.
+
 - Issue #8966: If a ctypes structure field is an array of c_char, convert its
   value to bytes instead of str (as done for c_char and c_char_p).