Issue #8838, #8339: Remove codecs.charbuffer_encode() and "t#" parsing format

Remove last references to the "char buffer" of the buffer protocol from
Python3.
diff --git a/Doc/whatsnew/3.2.rst b/Doc/whatsnew/3.2.rst
index 265f928..14f9215 100644
--- a/Doc/whatsnew/3.2.rst
+++ b/Doc/whatsnew/3.2.rst
@@ -173,4 +173,7 @@
 
 * bytearray objects cannot be used anymore as filenames: convert them to bytes
 
+* "t#" format of PyArg_Parse*() functions has been removed: use "s#" or "s*"
+  instead
+
 * Stub