[DRAFT] NetworkX 3 support

[bdpedigo]

No description provided.

too early

[bdpedigo]

@fcollman looks like tests are failing generally (i.e. before this PR) is that a known thing I shouldn't worry about?

[bdpedigo]

@fcollman @ceesem would like to bring this back up - i'd like to not have to pin networkx to be <3. Looking back at my changes here, I think it could make sense to just have a function/method for

if nx.__version__ < 3:
   G = nx.from_scipy_sparse_matrix(nrn.mesh.csgraph)
else:
  G = nx.from_scipy_sparse_array(nrn.mesh.csgraph)

(I think all other diffs were from my autoformatter here)

[bdpedigo]

I also don't know whether/how to trust tests here since they seem like they've been failing since I submitted this, lmk any thoughts on that