Revisions 530, 531

Released to 8.0/edge
OCI images:

• {'resource_name': 'mysql-router-image', 'revision': 58}

What's Changed

• Run juju 3.6 nightly tests against 3.6/stable by @shayancanonical in #337
• [DPE-4573] Update MySQL to v8.0.39 by @shayancanonical in #308

Full Changelog: rev529...rev531