MailjetConfigurationAccessCheck triggers on all routes

Fixed in MR !61.

I want to raise this to critical, because this problem can make a website completely inaccessible (access denied on all routes)

Patch to fix MailjetConfigurationAccessCheck to properly validate route requirements.

Thanks. This page was needed and functionnal on Drupal 9.5.11

The patch in #6 does not seem to apply for the latest 4.0.2 version so i recreated the patch.

+1 for the fix, as at the moment all routes return "Access denied"

The fix from the MR works.