Resolve "Make `ParamSpaceGroup.select ` and `MultiversePlotCreator` more robust for zero volume parameter spaces"

What does this MR do?

This MR fixes issues with ParamSpaces of volume 0, i.e.: those where no parameter dimension was defined.

Adjust ParamSpaceGroup.select for cases with ParamSpace of volume 0:

• Add error message if select contains the subspace key (cannot do anything with that one)

Can this MR be accepted?

• Implemented the changes
• Tests added
• Pipeline passes
• Changelog entry added
• Bumped version to 0.4.1 (bug fix release)

Anything to double-check?

Related issues

Closes #32 (closed)