Provisional backport to 3.11

[Gouvernathor]

The changes required are few (90526b4) and costs almost nothing to maintain.
Apparently there is no simple way for exporting two wheels from two branches for the same release.
Toolforge's maximal version is 3.11 at the moment.
The required version can be raised back to 3.12 as soon as parliamentdiagram can support it.

[Gouvernathor]

This issue stays open until the version rises back to 3.12.