gaas example uses old naming convention of rascaline

[DavideTisi]

as a title the naming convention of gaas example is the "old" one, New version of rascaline uses the convention introduced in pr 285.

To be clear the example is not broken because it pins the version of rascaline but with a new version of rascaline installed it would fail.
I do this issue as a reminder of the problem. Probably, it is worth fixing when we have a more stable version of rascaline maybe when there will be the pypi release