[REF][PHP8.2] Fix use of self in callables deprecation

[braders]

Overview

Fix Use of "self" in callables is deprecated issue.

Before

Fixes use of a syntax deprecated in PHP 8.2.

More detail on the deprecation can be found at https://php.watch/versions/8.2/partially-supported-callable-deprecation.

After

Use of a PHP 8.2 valid syntax.

Comments

This fixes a very recent change made here bafcc24. Ping @eileenmcnaughton, you are likely not aware that you used a syntax that is now deprecated in the latest version of PHP.

This is the same fix as was previously merged for another class here: #25625

[civibot]

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[eileenmcnaughton]

Thanks for the fix @braders & for making sure I saw it - hopefully it will sink into my pre-coffee brain