anaconda/pip repo Windows, not exclude py37, unification conda/pip dependencies

• setup Anaconda/pip repository for Windows and add the pycairo wheels from https://www.lfd.uci.edu/~gohlke/pythonlibs/, see https://gitlab.aicrowd.com/flatland/flatland/blob/461c5cfe1aff9dd93df580cf99f162bd3036a484/setup.py
• get rid of conda-only dependencies?
• refer in tox.ini so py37 runs also under Windows