Deleted user does not remove account from group

[withanhdammit]

Describe the bug

One person left the company, his account was deleted from 'users'. Further investigation showed he was still a member of 'Monitoring Users' group, however when an attempt to remove from the group is made, it errors and does not remove the user
"Zend_Form_Element::_filterValue(): Argument #2 ($key) must be passed by reference, value given"

To Reproduce

Add user, add user account to group
Delete user, attempt to delete from group

Expected behavior

User account should be deleted from groups when the account is deleted

Screenshots

Your Environment

Include as many relevant details about the environment you experienced the problem in

• Icinga Web 2 version and modules (System - About):
  2.12.1

• Web browser used:
  Chrome or Edge

• Icinga 2 version used (icinga2 --version):
  r2.14.0-1

• PHP version used (php --version):
  8.0

• Server operating system and version:
  Debian 10

Additional context

Add any other context about the problem here.

[nilmerg]

"Zend_Form_Element::_filterValue(): Argument #2 ($key) must be passed by reference, value given"

Please upgrade icinga-php-thirdparty to v0.12.1.

[nilmerg]

Duplicate of #3978