new version of Snudda and fixes in dependencies

This MR:

• adds py-snudda@1.4.0
• py-snudda inherits from PythonPackage (wasn't possible with our previous version of Spack+built distributions)
• fixes some issues with missing/incomplete dependencies on py-snudda and the packages it depends on (particularly py-bluepyopt)

changed the description

Hi @hjorth,

This MR adds py-snudda@1.4.0 and fixes the issue in !259 (closed), that was caused by missing/incomplete dependencies.

I also made some modifications to the Snudda Spack package, and I specified the required versions for all dependencies (as were listed in your setup.py and requirements.txt). Please check that everything is correct.

In the future, to add a new version of Snudda, you need to:

• add only one line for the version, e.g. version("1.5.0", "<hash>"). The url is calculated automatically by Spack from the pypi field
• add/update any new dependencies. For example if Snudda no longer works with bluepyopt 1.11.7, but needs >1.12, add this statement: depends_on("py-bluepyopt@1.12:", type=("build","run"), when=@15.0:)
• check if the new versions that are needed are already provided. If not, you need to add them (the same way you add the Snudda versions). I added you as a maintainer to all the packages that have been added to the repo as dependencies of Snudda, so with a quick search you can find all of them.

I'll merge this later today, so please have a quick look and let me know if everything is ok with the py-snudda package.

mentioned in commit d43b7ef8

merged