Migration guide v2.8.0

Migrate powsybl-core version to v4.7.0

In this release, powsybl-core version has been updated from version 4.6.1 to 4.7.0. No corresponding migration issue should affect you directly on powsybl-line-diagram. Nonetheless, if you are also using powsybl-core directly, please refer to powsybl-core migration guide to fix any issue due to that migration.

Force substation layout

The ForceSubstationLayout class and therefore powsybl-single-line-diagram-force-layout artifact have been removed, as the layout results were not convincing.