bpo-31170: Update libexpat from 2.2.3 to 2.2.4 (#3315)

* bpo-31170: Update libexpat from 2.2.3 to 2.2.4

Fix copying of partial characters for UTF-8 input (libexpat bug 115):
https://github.com/libexpat/libexpat/issues/115

* Add NEWS entry.
20 files changed