bpo-46932: Update bundled libexpat to 2.4.7

[zooba]

https://bugs.python.org/issue46932

[hartwork]

The pyexpatns.h part should probably not be dropped, please see the comment below.

The PR is likely good once it passes this Dockerfile of mine (and it does not, yet):

# Copyright (c) 2022 Sebastian Pipping <sebastian@pipping.org>
# Licensed under the Apache License version 2.0

FROM alpine
RUN apk add --update \
            diffutils \
            git \
            sed \
        && \
    git clone --depth 1 https://github.com/python/cpython cpython-main \
        && \
    ( cd cpython-main && git rev-parse HEAD ) \
        && \
    git clone --depth 1 --branch bpo-46932 https://github.com/zooba/cpython zooba-bpo-46932 \
        && \
    ( cd zooba-bpo-46932 && git rev-parse HEAD ) \
        && \
    git config --global advice.detachedHead false \
        && \
    git clone --depth 1 --branch R_2_4_6 https://github.com/libexpat/libexpat libexpat_2_4_6 \
        && \
    git clone --depth 1 --branch R_2_4_7 https://github.com/libexpat/libexpat libexpat_2_4_7 \
        && \
    diff -r -u libexpat_2_4_6/expat/lib/ cpython-main/Modules/expat/ | tee 2-4-6.diff \
        && \
    diff -r -u libexpat_2_4_7/expat/lib/ zooba-bpo-46932/Modules/expat/ | tee 2-4-7.diff \
        && \
    sed -e '/^Only in /d' -e '/^\(+++\|---\) /d' -e '/^diff /d' -i 2-4-6.diff 2-4-7.diff \
        && \
    diff -u 2-4-6.diff 2-4-7.diff \
        && \
    echo 'Diff is good.'

[miss-islington]

Thanks @zooba for the PR 🌮🎉.. I'm working now to backport this PR to: 3.7, 3.8, 3.9, 3.10.
🐍🍒⛏🤖

[bedevere-bot]

GH-31738 is a backport of this pull request to the 3.10 branch.

[bedevere-bot]

GH-31739 is a backport of this pull request to the 3.9 branch.

[bedevere-bot]

GH-31740 is a backport of this pull request to the 3.8 branch.

[bedevere-bot]

GH-31741 is a backport of this pull request to the 3.7 branch.