Add changelog entries for php-src GH-8388

[nielsdos]

I probably butchered something at least. They have UPGRADING entries, but let's already make a PR for them.

EDIT: called it :') but the pesky whitespace was already there >:( :p

[nielsdos]

FTR: this shouldn't be merged as this change was undone. I plan on introducing this in another way during the 8.4 cycle though so we can still keep this PR around, just not for 8.3.

[kamil-tekiela]

Converting it to draft for the time being.