Remove dependency louvain and leidenalg

[dmalzl]

I am trying to install doubletdetection but fail to do so due to an error while building the louvain dependency. From what I get from the code it seems that these algorithms are anyway handled by scanpy, which should also install all the necessary dependencies and in my case installs just fine. Thus my question is if it is even necessary to have louvain and leidenalg in the dependencies when they are anyway handled somewhere else

[yuanjianwen-gif]

same problem, fail with installing louvain