Replace deprecated variable interpolation syntax in PHP 8.2

[JoyceBabu]

Using ${var} in strings is deprecated. This is the only instance where the deprecated syntax is used.

[pprkut]

@danhunsaker I can't merge this myself because of the branch protection rules, and don't have permission to check/update those 🙁

[danhunsaker]

@JoyceBabu Sorry for the delay on this. We can't quite merge until this gets a rebase, unfortunately, and it looks like we don't have permissions to update your PR. Can you rebase this?

@pprkut That should be fixed, now. Had the rules too restrictive, as you noted above. I'll try to figure out boosting your permissions, though I don't have much control over that since we're in Resque's namespace.

[pprkut]

@danhunsaker Thank you! Much appreciated 🙂

[JoyceBabu]

I have rebased the commit.