Upgrade civix for PHP8 compatibility

[mlutfy]

hi @kurund, would it be possible to upgrade civix and tag a new release for PHP8 compatibility? https://civicrm.org/blog/bgm/php-8-support-civicrm-extensions

I had to remove the "reviewed" status of the extension for now, so that people do not break their CiviCRM installation. I will add it back when it's fixed. https://civicrm.org/extensions/simple-donate

[mlutfy]

ps: would you like us to migrate this to Gitlab so that it is community-maintained? (minor fixes, no big changes unless you assign another maintainer).