issue when installing with conda

[LoreMoretti]

(robsub) lomoretti@IITICUBLAP226:~$ conda install -c conda-forge gz-sim8
Channels:
 - conda-forge
Platform: linux-64
Collecting package metadata (repodata.json): done
Solving environment: failed

InvalidMatchSpec: Invalid spec 'coinhsl[url=file:///home/lomoretti/Downloads/coinhsl-2019.05.21.1-h11d5e8e_0.tar.bz2]': Libmamba only supports a subset of the MatchSpec interface for now. You can only use ('name', 'version', 'build', 'channel', 'subdir'), but you tried to use ('url',).

cc @traversaro