Merge 4.7 into 4.8

[mongodb-php-bot]

Merge new changes from 4.7 into 4.8.

Commits

• PHPORM-227 Fix single document upsert (PHPORM-227 Fix single document upsert #3100): efab63b

Resolving conflicts

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

git merge 4.8

Ignoring changes

To ignore from the remote branch, first reset the temporary branch to 4.8 and manually merge using the `ours` merge strategy:

git reset --hard 4.8
git merge --strategy=ours 4.7

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