Rollback version bump

doctrine/dbal 2.6 requires PHP 7.1

Add an extra check here

Serialize models with Mail::queue

Not sure if Queueable will have any affect, let's add it for good measure.

Fixes octobercms/october#3095

Fix signature in latest Laravel

Looks like they've recently added a secondLocalKey (named secondOtherKey in October)
Fixes octobercms/october#3083

Add backward compatibility for Mail::queue

Fixes octobercms/october#3025

Set the relation manually after create

This should occur as part of create() -> add() but unit tests suggest otherwise

Fixes bad twig version

Refs octobercms/october#2908

Add woff2 to the list of asset extensions

Add woff2 to the list of asset extensions