This update for icinga2 fixes the following issues:

Update to 2.12.4

* Bugfixes

- Fix a crash when notification objects are deleted using the
API #8782
- Fix crashes that might occur during downtime scheduling if
host or downtime objects are deleted using the API #8785
- Fix an issue where notifications may incorrectly be skipped
after a downtime ends #8775
- Don't send reminder notification if the notification is still
suppressed by a time period #8808
- Fix an issue where attempting to create a duplicate object
using the API might result in the original object being
deleted #8787
- IDO: prioritize program status updates #8809
- Improve exceptions handling, including a fix for an uncaught
exception on Windows #8777
- Retry file rename operations on Windows to avoid intermittent
locking issues #8771

* Enhancements

- Support Boost 1.74 (Ubuntu 21.04, Fedora 34) #8792

Update to 2.12.3

* Security

- Fix that revoked certificates due for renewal will
automatically be renewed ignoring the CRL
(Advisory / CVE-2020-29663 - fixes boo#1180147 )

* Bugfixes

- Improve config sync locking - resolves high load issues on
Windows #8511
- Fix runtime config updates being ignored for objects without
zone #8549
- Use proper buffer size for OpenSSL error messages #8542
* Enhancements
- On checkable recovery: re-check children that have a problem
#8506

Update to 2.12.2

* Bugfixes

- Fix a connection leak with misconfigured agents #8483
- Properly sync changes of config objects in global zones done
via the API #8474 #8470
- Prevent other clients from being disconnected when replaying
the cluster log takes very long #8496
- Avoid duplicate connections between endpoints #8465
- Ignore incoming config object updates for unknown zones #8461
- Check timestamps before removing files in config sync #8495

* Enhancements

- Include HTTP status codes in log #8467