Update PHPStan to 2.1.19

Seems like a non breaking change.

Is there a particular reason to bump this by two patch versions mid-cycle? Bug fixes we want or suchlike? It does not seem to substantively affect the baseline, just that one hunk.

Do we want to wait for a larger jump?

17 to 21 seems like a good jump to me.

This is a larger jump, including pphpstan-drupal now too. And, IMHO it's better keep PHPStan updated no-matter-what, because it prevents errors to be committed, not just shows the ones that exist.

I agree!