Investigate Dependabot improvements wrt release notes

[SaschaSchwarze0]

In Enable dependabot updates #1044, we enabled Dependabot updates for this repository. As part of that we changed the release notes linter to ignore Dependabot PRs because the Dependabot configuration does not allow to define the PR description and therefore cannot have a release note section.

The side effect of that is that release notes will never contain Dependabot updates. We might want to change this, especially as Dependabot updates are security-relevant.

One idea was to update the release notes generation to specifically handle Dependabot PRs. But there might be other approaches.