Publish conda package

gsfpy is published as a pip package to PyPI as part of the automated CI process. To support as wide a developer audience as possible, we should also publish to Conda.

ACs

• GitHub actions updated to publish master version to Conda
• Following publication, gsfpy can be installed using the command conda install gsfpy
• Documentation: README updated with instructions on how to install using Conda

See the below relevant links

https://docs.conda.io/projects/conda-build/en/latest/user-guide/tutorials/build-pkgs-skeleton.html
https://docs.conda.io/projects/conda-build/en/latest/user-guide/tutorials/build-pkgs.html