build(deps): bump ansible-core from 2.15.4 to 2.15.8 in /tools/dev

Bumps [ansible-core](https://github.com/ansible/ansible) from 2.15.4 to 2.15.8.
- [Release notes](https://github.com/ansible/ansible/releases)
- [Commits](ansible/ansible@v2.15.4...v2.15.8)

---
updated-dependencies:
- dependency-name: ansible-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

tools/dev/requirements_antsibull.txt

@@ -14,5 +14,5 @@
 # older version of ansible is needed for ansible-oracle
 # otherwise the ansible-doc gets errors due to problems with ansible-oracle-modules
 # They need some refactoring...
-ansible-core==2.15.4
+ansible-core==2.15.8
 antsibull-changelog==0.23.0