Service providers order

[guiwoda]

As reported on the Slack channel, the GedmoExtensionsServiceProvider and the DoctrineServiceProvider may have interdependencies that fail when not properly ordered.

This was reported as not working:

[
    // ...
    DoctrineServiceProvider::class,
    GedmoExtensionsServiceProvider::class,
]

and this was reported as working:

[
    // ...
    GedmoExtensionsServiceProvider::class,
    DoctrineServiceProvider::class,
]