PYTHON-5357 Update changelog for 4.12.1 release

[aclark4life]

No description provided.

[blink1073]

LGTM! The link failure should be resolved, I kicked the build.

[blink1073]

drivers-pr-bot please backport to v4.12

[mongodb-drivers-pr-bot]

Sorry, unable to cherry-pick to v4.12, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout -b cherry-pick-v4.12-08e7f036a22b1ee38bed9793d494b7f5fe174c04 v4.12

git fetch origin 08e7f036a22b1ee38bed9793d494b7f5fe174c04

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 08e7f036a22b1ee38bed9793d494b7f5fe174c04

3. You will likely have some merge/cherry-pick conflicts here, fix them and commit:

git commit -am {message}

4. Push to a named branch:

git push origin cherry-pick-v4.12-08e7f036a22b1ee38bed9793d494b7f5fe174c04

5. Create a PR against branch v4.12. I would have named this PR:

"PYTHON-5357 Update changelog for 4.12.1 release (#2321) [v4.12]"