Merge 5.4 into 5.x

[mongodb-php-bot]

Merge new changes from 5.4 into 5.x.

Commits

• DOCSP-50960: Install PHP ext with pie (DOCSP-50960: Install PHP ext with pie #3419) (DOCSP-50960: Install PHP ext with pie (#3419) #3426): 1bb06ec
• DOCSP-51402: schema-flexible terminology (DOCSP-51402: schema-flexible terminology #3424): a2b7773

Resolving conflicts

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

git merge 5.x -m "Resolve conflicts in 5.x"

Ignoring changes

To ignore from the remote branch, first reset the temporary branch to 5.x and manually merge using the `ours` merge strategy:

git reset --hard 5.x
git merge --strategy=ours 5.4 -m "Ignore changes from 5.4"

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