src/poky:python3: upgrade 3.12.2 -> 3.12.3

Remove the following patch:

0001-gh-115133-Fix-tests-for-XMLPullParser-with-Expat-2.6.patch

Which a different fix was submitted for in:

c4fa79b924 [3.12] gh-115133: Fix tests for XMLPullParser with Expat 2.6.0 (GH-115164) (GH-115288)
See: python/cpython#115288
(related to CVE-2023-52425)

Changelog: https://docs.python.org/3/whatsnew/changelog.html#python-3-12-3-final

(From OE-Core rev: 4122d8f6ecf6957de7a34fc51beffcd8e808911f)

Signed-off-by: Trevor Gamblin <[email protected]>
Signed-off-by: Richard Purdie <[email protected]>

Author: threexc