\Drupal\Component\Assertion\Inspector::assertTraversable is deprecated

[github-actions]

https://www.drupal.org/node/3422775

Introduced in branch/version: 10.3.x / 10.3.0

\Drupal\Component\Assertion\Inspector::assertTraversable is deprecated in 10.3.0 and removed in 11.0.0. Use is_iterable instead.

Before:

if (Inspector::assertTraversable($traversable)) {
  // ...
}

After:

if (is_iterable($traversable)) {
  // ...
}