chore: regenerate composer.lock (refresh dev dependencies)

Regenerate the lock from the manifest so it is in sync (fixes the CI
`composer install` failure) and refresh dependencies in the process —
firebase/php-jwt v7.0.4 -> v7.1.0 plus 11 others, with vendor-prefixed
re-strauss'd to match. Full wpunit suite passes against the updated deps
(305 tests, 835 assertions).

Author: kidunot89