[D7 PHP 8.1] Deprecated Serializable interface - update libphonenumber to ^8.12.

Upgraded to "giggsey/libphonenumber-for-php": "^8.12".

Then had to:

1. Update the consolidated composer.json file.
2. Then run composer update in the file directory /SITE_DIR/sites/default/files/composer (which is the path listed at /admin/config/system/composer-manager/settings)

Now the error is gone, but when I go to /admin/config/system/composer-manager, I get:

    Warning: Undefined array key "name" in composer_manager_installed_packages() (line 325 of /SITE_DIR/sites/all/modules/composer_manager/composer_manager.admin.inc).
    Warning: Undefined array key "version" in composer_manager_installed_packages() (line 326 of /SITE_DIR/sites/all/modules/composer_manager/composer_manager.admin.inc).
    Warning: Trying to access array offset on value of type bool in composer_manager_installed_packages() (line 325 of /SITE_DIR/sites/all/modules/composer_manager/composer_manager.admin.inc).
    Warning: Trying to access array offset on value of type bool in composer_manager_installed_packages() (line 326 of /SITE_DIR/sites/all/modules/composer_manager/composer_manager.admin.inc).
    Warning: Undefined array key "name" in composer_manager_installed_packages() (line 325 of /SITE_DIR/sites/all/modules/composer_manager/composer_manager.admin.inc).
    Warning: Undefined array key "version" in composer_manager_installed_packages() (line 326 of /SITE_DIR/sites/all/modules/composer_manager/composer_manager.admin.inc).
    The following packages must be installed: giggsey/libphonenumber-for-php
    Refer to the instructions on the Composer Manager project page for updating packages.

Requires [3247179] in order to fix the warnings.

1. Apply patch https://git.drupalcode.org/project/composer_manager/-/merge_requests/6.diff in [3247179]
2. Upgrade giggsey/libphonenumber-for-php to ^8.12
   • the first release that supports PHP 8.1: https://github.com/giggsey/libphonenumber-for-php/releases/tag/8.12.34
3. Add instructions for users to then:
   1. Update the consolidated composer.json file at /admin/config/system/composer-manager
   2. Run composer update in the file directory /SITE_DIR/sites/default/files/composer
   • (which is the path listed at /admin/config/system/composer-manager/settings)