dev: Pin SciPy<1.3.0; fix MPI4PY error (#423)
dev: Pin SciPy<1.3.0; fix MPI4PY error (#423)

Pin SciPy <1.3.0 as workaround for Pymanopt. See:
https://github.com/pymanopt/pymanopt/issues/77

Require MPI4PY>=3 to fix Conda on MacOS. See:
https://travis-ci.org/brainiak/brainiak/jobs/545838666

Also, remove dependency on Typing, which is included in the Python
standard library starting with version 3.5, which is now the minimum
version we require.

mihaic/brainiak,lcnature/brainiak,lcnature/brainiak,CameronTEllis/brainiak,CameronTEllis/brainiak,mihaic/brainiak,CameronTEllis/brainiak,brainiak/brainiak,brainiak/brainiak,lcnature/brainiak,mihaic/brainiak,brainiak/brainiak