Laravel 9 support

[sgarwood]

Opened corresponding PR on ADLDAP/799

Tests are passing locally. Let me know if I need to add any additional tests or if the CI needs updating.

Let me know if any further work is required, happy to put in the work to get this merged.

To test locally add

 "repositories": [
        {
            "type": "vcs",
            "url": "https://github.com/sgarwood/Adldap2.git"
        }
    ],

and

  "adldap2/adldap2": "dev-patch-1",

to your package.json.