Quick fix for to adapt base_network for changes in voltage rebase

[ekatef]

Needed to make base_network functional for networks with DC lines.

Changes proposed in this Pull Request

Adapt a workflow to the networks with DC lines after changes introduced by #999 and #978.

Checklist

• [x] I consent to the release of this PR's code under the AGPLv3 license and non-code contributions under CC0-1.0 and CC-BY-4.0.
• [x] I tested my contribution locally and it seems to work fine.
• [ ] Code and workflow changes are sufficiently documented.
• [ ] Newly introduced dependencies are added to envs/environment.yaml and doc/requirements.txt.
• [ ] Changes in configuration options are added in all of config.default.yaml and config.tutorial.yaml.
• [ ] Add a test config or line additions to test/ (note tests are changing the config.tutorial.yaml)
• [x] Changes in configuration options are also documented in doc/configtables/*.csv and line references are adjusted in doc/configuration.rst and doc/tutorial.rst.
• [ ] A note for the release notes doc/release_notes.rst is amended in the format of previous release notes, including reference to the requested PR.

[ekatef]

@davide-f @pz-max by any chance, could you have time to review this? 🙏🏽

My feeling is that it's a rather urgent fix, as due currently countries with DC lines are not functional, unless force_ac: true is applied.

[ekatef]

Thanks @ekatef ! Great catch! It may be interesting to add a minor bug fix into release note, what do you think? Feel free to merge autonomously with any comment in the release not or without

Thanks a lot @davide-f! Yeah, the release notes actually needed some update :) Then I'd merge it, once CI would be happy.