Replace array_merge with array spread PHP < 8.1

infodroid

The recently introduced quick refactoring to replace array_merge with array spread should not show up when PHP version is < 8.1 (e.g. "php.version": "7.4") unless you are 100% certain no string-keyed arrays are involved, otherwise you get a fatal error after replacing.
Cheers

JakubMisek

infodroid, thank you for pointing this out.

We'll restrict the code action for PHP >= 8.1, because we can't determine for sure that the arrays are keyless.