conda package is architecture dependent although it could be noarch

[maxnoe]

Describe the bug

You currently build conda-packages for each os / python version, however, ctlearn is a pure python package that is not os-dependent.

It is enough to build a single, noarch: python package.

To Reproduce

https://anaconda.org/ctlearn-project/ctlearn/files

Expected behavior

Only a single noarch package for a pure python package without native, compiled components.

Supporting information

Add build.noarch: python to your recipe to fix.