Update to oik-user v0.9.0 for support for PHP 8.1, PHP 8.2 and PHP 8.3

Changes
| Change | Reference |
|---|---|
| Changed: Support PHP 8.1, PHP 8.2 and PHP 8.3 | bobbingwide/oik-user#8 |
| Changed: Prevent oiku_contact_user from working | bobbingwide/oik-user#6 |
| Changed: Don’t respond to oik_add_shortcodes unless oik’s activated. | bobbingwide/diy-oik#5 |
Tested
- Tested: With WordPress 6.4.1 and WordPress Multisite
- Tested: With PHP 8.1, PHP 8.2 and PHP 8.3
- Tested: With PHPUnit 9.6
