Remove conda recipe yml file after package distributed via conda-forge

[bobleesj]

The meta.yml file in the diffpy.srfit conda-forge recipe under review is different from what is provided in the current directory: conda-forge/staged-recipes#25665.

Seems like we already have diffpy.srfit conda package available here: https://anaconda.org/diffpy/diffpy.srfit, but it's not via the conda-forge channel.

We shall only delete these conda-recipe files (5-year old) once we have diffpy.srfit available on conda-forge.

Addressing: #85