conda-forge package depends on scipp

[jl-wynen]

We intentionally did not add scipp as a dependency to plopp so that we can install plopp when building and testing scipp. However, the conda-forge package depends on scipp. So we can no longer make clean envs for scipp with installed packages.

How do we address this? Do we remove scipp as a dependency on conda-forge and thereby make the package unusable is installed standalone? Or do we change how we make envs for scipp?

[nvaytet]

I think there was an issue with not having Scipp as a dependency on conda forge (the package didn't build or something).
But I don't remember exactly, @MridulS knows more.

[MridulS]

I was able to build the package, but we also need to make sure the package atleast passes the import test to get it on conda-forge, and without scipp plopp was failing that.

But now we can remove scipp from the deps as we have lazy loading #405, so the conda package should atleast pass the test. We are just tricking the import test here and the conda package isn't really useful without scipp. We can update our docs to always ask users to install scipp and plopp both when they are using plopp, or we can have something like plopp-base which is built without a scipp dependency.