[6.x] fix PHP8.4 deprecations

[JulienRAVIA]

I know this deprecations are handled on superior versions, but in our company we are still on Elastic Search 6.x so we need this version.

[ruflin]

Hi @JulienRAVIA Thanks for the PR. I have learned the hard way, that I better don't get PRs into branches which are not maintained anymore. Even though it looks like probably nothing should break, it still might break something (been there).

So I wonder what we can do here for you. Do you need the PR merged somewhere in the Elastica repo or can you pull the changes from your repository? If not, we could a branch with something like 6.x-julien so you could pull form this branch?