Merge v1.18 into master

[mongodb-php-bot]

Merge new changes from v1.18 into master.

Commits

• Prepare 1.18.1 release (Prepare 1.18.1 release #1534): b795048
• Back to -dev: 6a49ef7
• Package 1.18.1: 451fec4

Resolving conflicts

To resolve any conflicts, check out the temporary branch and run the following command:

git merge master

Ignoring changes

To ignore from the remote branch, first reset the temporary branch to master and manually merge using the `ours` merge strategy:

git reset --hard master
git merge --strategy=ours v1.18

Then, push the temporary branch to upate the pull request.

[alcaeus]

Note: I'll rebase this PR after #1533 is merged.

[alcaeus]

Manually merged using the ours strategy as the changes in phongo_version don't need to be included.