Update CHANGELOG.md

Signed-off-by: Norman Ziegner <n.ziegner@hzdr.de>

Author: Normo

CHANGELOG.md

@@ -30,6 +30,7 @@
 
 **Merged pull requests:**
 
+- Prepare release version 6.0.0 [\#437](https://github.com/hifis-net/ansible-collection-toolkit/pull/437) [[zammad](https://github.com/hifis-net/ansible-collection-toolkit/labels/zammad)] [[gitlab_runner](https://github.com/hifis-net/ansible-collection-toolkit/labels/gitlab_runner)] [[haproxy](https://github.com/hifis-net/ansible-collection-toolkit/labels/haproxy)] ([Normo](https://github.com/Normo))
 - Remove official support for EOL Ubuntu 20.04 [\#436](https://github.com/hifis-net/ansible-collection-toolkit/pull/436) [[unattended_upgrades](https://github.com/hifis-net/ansible-collection-toolkit/labels/unattended_upgrades)] [[zammad](https://github.com/hifis-net/ansible-collection-toolkit/labels/zammad)] [[ssh_keys](https://github.com/hifis-net/ansible-collection-toolkit/labels/ssh_keys)] [[gitlab_runner](https://github.com/hifis-net/ansible-collection-toolkit/labels/gitlab_runner)] [[keepalived](https://github.com/hifis-net/ansible-collection-toolkit/labels/keepalived)] [[haproxy](https://github.com/hifis-net/ansible-collection-toolkit/labels/haproxy)] [[netplan](https://github.com/hifis-net/ansible-collection-toolkit/labels/netplan)] [[redis](https://github.com/hifis-net/ansible-collection-toolkit/labels/redis)] [[gitlab](https://github.com/hifis-net/ansible-collection-toolkit/labels/gitlab)] ([Normo](https://github.com/Normo))
 - Test gitlab-runner version 18.0.2 with molecule [\#434](https://github.com/hifis-net/ansible-collection-toolkit/pull/434) [[gitlab_runner](https://github.com/hifis-net/ansible-collection-toolkit/labels/gitlab_runner)] ([Normo](https://github.com/Normo))
 - Install HAProxy 3.2 by default [\#433](https://github.com/hifis-net/ansible-collection-toolkit/pull/433) [[haproxy](https://github.com/hifis-net/ansible-collection-toolkit/labels/haproxy)] ([Normo](https://github.com/Normo))